Circus performer to take flight, we hear? (4)
I believe the answer is:
flea
'circus performer' is the definition.
(I've seen this before)
'take flight we hear?' is the wordplay.
'take flight' becomes 'flee' (synonyms).
'we hear?' shows a homophone (sound like).
'flee' is a homophone of 'FLEA'.
'to' acts as a link.
(Other definitions for flea that I've seen before include "high-jumper" , "Leaping insect" , "Irritating jumper?" , "Bug" , "tiny jumper" .)