| Underdeveloped ones | 19 |
| Underdeveloped nations | 22 |
| Underdeveloped countries | 24 |
| Undercut | 8 |
| Undercroft | 10 |
| Undercover? | 11 |
| Undercover, informally | 22 |
| Undercover, for short | 21 |
| Undercover, briefly | 19 |
| Undercover worker, perhaps | 26 |
| Undercover worker | 17 |
| Undercover wear? | 16 |
| Undercover types | 16 |
| Undercover type | 15 |
| Undercover time? | 16 |
| Undercover surveillance vehicle, perhaps | 40 |
| Undercover sort | 15 |
| Undercover police operation | 27 |
| Undercover Playboy bunny of 1963 | 32 |
| Undercover person | 17 |
| Undercover outfit? | 18 |
| Undercover org. | 15 |
| Undercover operator | 19 |
| Undercover operative | 20 |
| Undercover operations where agents can bring guests? | 52 |
| Undercover operations | 21 |
| Undercover operation to trap a letter? | 38 |
| Undercover operation | 20 |
| Undercover op | 13 |
| Undercover officer's shout, upon revealing him or herself | 61 |
| Undercover men | 14 |
| Undercover man | 14 |
| Undercover jobs | 15 |
| Undercover item? | 16 |
| Undercover item | 15 |
| Undercover group: Abbr. | 23 |
| Undercover enterprise | 21 |
| Undercover drug agents | 22 |
| Undercover drug agent | 21 |
| Undercover device | 17 |
| Undercover cops | 15 |
| Undercover cop? | 15 |
| Undercover cop, perhaps | 23 |
| Undercover cop, maybe | 21 |
| Undercover cop, at times | 24 |
| Undercover cop of 1970s TV | 26 |
| Undercover cop | 14 |
| Undercover buster | 17 |
| Undercover apparatus | 20 |
| Undercover agt. | 15 |
| Undercover agents | 17 |
| Undercover agent? | 17 |
| Undercover agent, in slang | 26 |
| Undercover agent's wear | 27 |
| Undercover agent's cover? | 29 |
| Undercover agent of a sort | 26 |
| Undercover agent | 16 |
| Undercover agcy. | 16 |
| Undercover activity? | 20 |
| Undercover | 10 |
| Undercooked, to some | 20 |
| Undercooked, perhaps | 20 |
| Undercooked, as eggs | 20 |
| Undercooked, as an egg | 22 |
| Undercooked meat danger | 23 |
| Undercooked | 11 |
| Underconfident utterances | 25 |
| Undercolored | 12 |
| Undercoats of paint | 19 |
| Undercoats a surface | 20 |
| Undercoating | 12 |
| Undercoat material | 18 |
| Undercoat for painting on wood | 30 |
| Undercoat applications | 22 |
| Undercoat | 9 |
| Underclothing | 13 |
| Underclassmen | 13 |
| Underclassman? | 14 |
| Undercarriage piece | 19 |
| Undercarriage parts | 19 |
| Undercarriage item | 18 |
| Undercard fight, for short | 26 |
| Undercard boxing bout | 21 |
| Underbrush cutter | 17 |
| Underbosses' bosses | 23 |
| Underboss | 9 |
| Underbodice | 11 |
| Underattended, say | 18 |
| Underarm product | 16 |
| Underarm | 8 |
| Underappreciated laborer | 24 |
| Underaged digger? | 17 |
| Underage temptation, slangily | 29 |
| Underage person | 15 |
| Underage one | 12 |
| Underage drinker's item | 27 |
| Underage drinker in Lincoln? | 28 |
| Underage child of a military officer? | 37 |
| Underage | 8 |
| Underachievers are not up to it | 31 |