Second gear for take-off (4)
I believe the answer is:
skit
'take-off' is the definition.
(both can mean a send-up or parody)
'second gear' is the wordplay.
'second' becomes 's' (common abbreviation).
'gear' becomes 'kit' (kit is a kind of gear).
's'+'kit'='SKIT'
'for' is the link.
(Other definitions for skit that I've seen before include "Burlesque - parody" , "Opportunity to take off" , "that may be produced by 19 [PARODIST]" , "Short satirical piece" , "Comic routine" .)