The answers to the clues below will have something in common.

1. Non-conformist's activity
2. Silly, foolish behavior
3. Mosquito breeding ground
4. It's known as "Insurance City"
5. You need it to get on a plane
6. Heavy equipment for leveling
7. Tumble-down, as a shed

Answers:

1. Buck the system
2. Tomfoolery
3. Stagnant pond
4. Hartford, Connecticut
5. Boarding pass
6. Bulldozer
7. Ramshackle - - - Each clue contains the name of a male animal.

Credit:
NY Times Crossword
October 24, 1999
Nancy Salomon 
MALE BONDING