Convince to pay in full (7)
I believe the answer is:
satisfy
This clue is a double definition.
'convince' is the first definition.
(thesaurus)
'pay in full' is the second definition.
(I've seen this before)
'to' acts as a link.
(Other definitions for satisfy that I've seen before include "Fulfill requirements" , "indulge" , "Meet the needs of (someone)" , "pay in full" , "Fulfil requirements" .)