| RABBITWARREN | Warrant bribe reforming underground system (6, 6) |
| SUBWAY | New York's underground system (6) |
| LONDON | City that has the oldest underground system (6) |
| SEWERS | Needle users found in underground systems (6) |
| SILVERMINE | 4's 17 in lines I"m constructing for underground system (6,4) |
| METRO | No Dart in Rotterdam or underground system (5) |
| EXUBERANT | Lavish underground system once operated with everything moving ahead of time |
| TESTTUBE | Scientific equipment needed to try out underground system (4-4) |
| TUBE | To be sure, dig out rose from overseas underground system (4) |
| PROTUBERANT | Outstanding rhetoric in support of underground system? |
| MAESTRO | Conductor, as, in parts, employed in underground system |
| RHIZOME | Greeting head of zoo in capital's underground system (7) |
| METRONOME | Device used by musicians in underground system? No, this person! (9) |
| SEWER | Part of an underground system |
| TUBER | Potato producing underground system before the end of October (5) |
| HONGKONG | City that has a busy underground system (4,4) |
| NEWYORKCITY | This has a busy underground system (3,4,4) |
| ROUTE | The way the underground system is heard (5) |
| ARROWROOT | One of those in the Marantaceae family in Dart and part of The Underground system (9) |
| ROOTLET | Small component of the underground system, part keeping old trains, primarily, on time |
