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

1. Ape
2. Read a second time
3. Speaking without words
4. Word before hot, as with a pie
5. Stage in a caterpillar's metamorphosis
6. Winter sight that grows with its foot on top and its head pointed down

Answers:

1. MIMIC
2. REREAD
3. MIMING
4. PIPING
5. COCOON
6. ICICLE

What they have in common:

The first two letters of each word are repeated as the third and fourth letters.