Do an impression of (5)
I believe the answer is:
mimic
'do an impression of' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for mimic that I've seen before include "Imitate satirically" , "Act like" , "Caricature" , "'Copy, imitate (5)'" , "Imitate for humorous reasons" .)