| On-line ticket service | 22 |
| On-location broadcasts | 22 |
| On-ramp posting, perhaps | 24 |
| On-screen nephrologist | 22 |
| On-screen surgery resident | 26 |
| On-screen trash can, e.g. | 25 |
| On-screen trash can, for one | 28 |
| On-site day care, perhaps | 25 |
| On-site shucking sites | 22 |
| On-the-go morning snack | 23 |
| On-the-green golf strokes | 25 |
| On-the-hour radio offering | 26 |
| On-the-job protection org. | 26 |
| On-the-job training slogan | 26 |
| On-the-playing-field animal | 27 |
| On-the-spot canvass of voters | 29 |
| On-the-spot TV programs | 23 |
| On-the-town time for many | 25 |
| On-the-way-out PC component | 27 |
| On-___ (bit of gossip) | 22 |
| Onager treading insect? | 23 |
| Onassis who married Jackie | 26 |
| Onassis's nickname | 22 |
| Onassis, to his friends | 23 |
| Onboard GPS suggestion | 22 |
| Once - lifetime connector | 25 |
| Once across the Rio Grande? | 27 |
| Once and quince, for example | 28 |
| Once around a racetrack | 23 |
| Once around the Brickyard | 25 |
| Once around the course | 22 |
| Once around the moon, e.g. | 26 |
| Once around the park, say | 25 |
| Once around, for John Glenn | 27 |
| Once around, to an astronaut | 28 |
| Once bitten, so to speak | 24 |
| Once bitten, twice ___ | 22 |
| Once more to Lil Abner | 23 |
| Once more from the top | 22 |
| Once more in the country? | 25 |
| Once more than two times | 24 |
| Once more, colloquially | 23 |
| Once more, country-style | 24 |
| Once more, Dogpatch-style | 25 |
| Once more, hillbilly-style | 26 |
| Once more, in Dogpatch | 22 |
| Once more, in the Ozarks | 24 |
| Once more, to Dizzy Dean | 24 |
| Once more, Western style | 24 |
| Once __ (every seven days) | 26 |
| Once ____ a time . . . | 22 |
| Once, but not nowadays | 22 |
| Once, once upon a time | 22 |
| Once-around-Sol period | 22 |
| Once-beautiful castle? | 22 |
| Once-common childhood ailment | 29 |
| Once-common childhood malady | 28 |
| Once-common commercial fuel | 27 |
| Once-common Georgia sights | 26 |
| Once-common skyline sights | 26 |
| Once-faddish aerobics regimen | 29 |
| Once-fashionable card game | 26 |
| Once-fashionable tableware | 26 |
| Once-fearsome extinct cat | 25 |
| Once-in-a-blue-moon events | 26 |
| Once-in-a-lifetime pilgrimage | 29 |
| Once-in-a-lifetime traveler | 27 |
| Once-popular anesthetic | 23 |
| Once-popular computers | 22 |
| Once-popular feather source | 27 |
| Once-popular street liners | 26 |
| Once-promising failures | 23 |
| Once-rare Sunday sights | 23 |
| Once-sacred slitherers | 22 |
| Once-scandalous exposure | 24 |
| Once-seedy section of NYC | 25 |
| Once-ubiquitous shoe retailer | 29 |
| Once-worshiped white wader | 26 |
| Once-worshipped white wader | 27 |
| Once-___ (quick appraisals) | 27 |
| Once-___ (quick examinations) | 29 |
| Once/a time go-between | 22 |
| Oncle's counterpart | 23 |
| Oncologist's suffix | 23 |
| Oncologist's suggestion | 27 |
| One ___ (sandlot game) | 23 |
| One 'twixt 12 and 20 | 24 |
| One "B" of B&B | 28 |
| One "born free" | 25 |
| One "C" in C.C.C. | 27 |
| One "fair of face" | 28 |
| One "in the woods" | 28 |
| One "little woman" | 28 |
| One "Pac-Man" ghost | 29 |
| One "T" of TNT | 24 |
| One - one of perhaps many | 25 |
| One / customer connector | 24 |
| One 13th of the month? | 22 |
| One 60-thousandth of a min. | 27 |
| One 60-trillionth of a min. | 27 |