Deny an increase to, for instance (7)
I believe the answer is:
gainsay
'deny' is the definition.
(I've seen this before)
'an increase to for instance' is the wordplay.
'an increase' becomes 'gain' (gain is a kind of increase).
'to for instance' becomes 'say' (both can be used to introduce an example).
'gain'+'say'='GAINSAY'
(Other definitions for gainsay that I've seen before include "Challenge, dispute" , "Contradict, deny, dispute" , "Speak against" .)