| On ___ (needing no human intervention) | 38 |
| On ___ (proceeding independently) | 33 |
| On ___ (proceeding successfully) | 32 |
| On ___ (with no assurance of sale) | 34 |
| On ___ (without assurance of payment) | 37 |
| On ___ basis (for testing purposes) | 35 |
| On ___ with (not speaking to, perhaps) | 38 |
| On ___ with (of equal magnitude) | 32 |
| On ____ : 1951 Danny Kaye film | 32 |
| On ____ Majesty's Secret Service | 36 |
| On ____: per detailed directions | 32 |
| On ____: with no assurance of sale | 34 |
| On _____ (freelancer's terms) | 33 |
| On-air performers, in TV advertising | 36 |
| On-board prognostication device? | 32 |
| On-line aid for shoppers' stops | 35 |
| On-line businesses, collectively | 32 |
| On-line chat components, for short | 34 |
| On-line news distribution system | 32 |
| On-line wiki for a popular sci-fi TV show | 41 |
| On-road vehicle requirement since 1996 | 38 |
| On-the-go Sony devices, for short | 33 |
| Once again part of an athletic clique? | 38 |
| Once Broadway's longest-running show | 40 |
| Once in a while (with "now") | 38 |
| Once powerful city-state of ancient Greece | 42 |
| Once-again fashionable soulful rock instruments | 47 |
| Once-autonomous people of southern Russia | 41 |
| Once-common "commonly" | 32 |
| Once-common desert fighting force | 33 |
| Once-common monochrome PC display | 33 |
| Once-common urban skyline sights | 32 |
| Once-dominant industry in Pittsburgh | 36 |
| Once-homeless "Golden-Voiced" Williams | 48 |
| Once-in-a-lifetime exchange, maybe | 34 |
| Once-in-a-lifetime trip, for some | 33 |
| Once-popular children's TV character | 40 |
| Once-popular diet soft drink, or part of the can | 48 |
| Once-powerful republic of NW Italy | 34 |
| Once-prominent Arby's competitor | 36 |
| Once-trendy Hollywood workout routine | 37 |
| Once-ubiquitous black-on-yellow image | 37 |
| One ''A'' in Paris | 34 |
| One "a-leaping" in a Christmas song | 45 |
| One "Arab Spring" nation | 34 |
| One "caught" on grainy film | 37 |
| One "coming" in a Three Dog Night hit | 47 |
| One "E" on a scoreboard | 33 |
| One "hissed" in a melodrama | 37 |
| One "in de cold, cold ground" | 39 |
| One "out" in la la land | 33 |
| One "tamed" in Shakespeare | 36 |
| One "Tarzan" portrayer | 32 |
| One about Jerry Springer debuted in 2003 | 40 |
| One above the Lötschberg Tunnel | 34 |
| One accepting the world as it is | 32 |
| One accustomed to the pole position? | 36 |
| One actor, or two American presidents | 37 |
| One actress, or two British prime ministers | 43 |
| One addressed as "lord" | 33 |
| One administering a Biblical punishment | 39 |
| One administering corporal punishment | 37 |
| One affecting elegant expression | 32 |
| One after another, as in a series | 33 |
| One akin to a Directioner, Selenator, or Swifty | 47 |
| One alternative from Howie Mandel | 33 |
| One always on the lookout for a deal | 36 |
| One always seeing the glass half full | 37 |
| One always seen in Häagen-Dazs? | 34 |
| One always sticking its nose in things | 38 |
| One always talking about his MacBook Air? | 41 |
| One among the nightingales, in a poem | 37 |
| One answer to ''Should we?'' | 44 |
| One answer to ''Wanna?'' | 40 |
| One answer to "How are you?" | 38 |
| One answer to an age-old question | 33 |
| One appealing to a meter reader? | 32 |
| One appears on the Australian Coat of Arms | 42 |
| One appointed by God, to believers | 34 |
| One arranging things in large categories | 40 |
| One arriving during the overture, say | 37 |
| One at an Occupy protest, probably | 34 |
| One at the bottom of the totem pole | 35 |
| One at the kids' table, perhaps | 35 |
| One at the wheel of a gherkinmobile? | 36 |
| One at Times Square on New Year's Eve | 41 |
| One attempting to clean out the house | 37 |
| One attracting considerable interest? | 37 |
| One author, or two English monarchs | 35 |
| One authorized to act for another | 33 |
| One available for future reference? | 35 |
| One avoiding the service entrance? | 34 |
| One barred from a U.N. no-fly zone | 34 |
| One begins "Rhapsody in Blue" | 39 |
| One begins parallel parking in it | 33 |
| One behind home plate, informally | 33 |
| One behind the wheel with a handle | 34 |
| One believing that God is indifferent | 37 |
| One billion years, in geologic time | 35 |
| One blatantly disobeying traffic laws | 37 |