Dispute on both sides to produce decline (10)
I believe the answer is:
degenerate
'decline' is the definition.
(I know that degenerate is a kind of decline)
'dispute on both sides to produce' is the wordplay.
'on both sides' means to remove the middle letters (the left and right sides of the word are used).
'to produce' becomes 'generate' (generating is a kind of producing).
'dispute' with its middle removed is 'de'.
'de'+'generate'='DEGENERATE'
(Other definitions for degenerate that I've seen before include "Corrupt type" , "Decline, deteriorate" , "Mean" , "sink" , "Showing evidence of decline" .)