Bird, catching bit of current, is to take off (7)
I believe the answer is:
lampoon
'is to take off' is the definition.
(both can mean to ridicule)
'bird catching bit of current' is the wordplay.
'bird' becomes 'loon' (loon is a kind of bird).
'catching' means one lot of letters goes inside another.
'bit of current' becomes 'amp' (unit of electrical current).
'loon' going around 'amp' is 'LAMPOON'.
(Other definitions for lampoon that I've seen before include "Literary satire" , "Satirise, ridicule" , "ridiculous scenario" , "Pool man (anag)" , "Make fun of" .)