Fixes wheels — it prevents issue (4)
I believe the answer is:
snip
'it prevents issue' is the definition.
(as in a vasectomy - issue can mean offspring)
'fixes wheels' is the wordplay.
'fixes' becomes 'pins' (pinning is a kind of fixing).
'wheels' is a reversal indicator (to wheel can mean to turn around).
'pins' back-to-front is 'SNIP'.
(Other definitions for snip that I've seen before include "Bargain - crop" , "Bargain (coll)" , "Cut - certainty" , "Cut with scissors - bargain" , "bargain buy" .)