Believe compliance is occasionally ignored (5)
I believe the answer is:
opine
'believe' is the definition.
(I've seen this before)
'compliance is occasionally ignored' is the wordplay.
'is occasionally ignored' means one should take alternating letters (ignore occasional letters and keep the rest).
The alternate letters of 'compliance' are 'OPINE'.
(Other definitions for opine that I've seen before include "Proffer a view" , "Say what one thinks" , "Express or hold view" , "Suppose" , "Give opinion" .)