Turn using second gear (4)
I believe the answer is:
skit
'turn' is the definition.
(I've seen this before)
'second gear' is the wordplay.
'second' becomes 's' (common abbreviation).
'gear' becomes 'kit' (kit is a kind of gear**).
's'+'kit'='SKIT'
'using' acts as a link.
(Other definitions for skit that I've seen before include "Parodic sketch" , "Short humorous act" , "A piece of humorous mimicry" , "Short comic piece" , "Comical sketch" .)