Made Vince and Dee provide proof (8)
I believe the answer is:
evidence
'proof' is the definition.
(thesaurus)
'made vince and dee' is the wordplay.
'made' indicates anagramming the letters.
'and' means one lot of letters go next to another (I've seen this in other clues).
'vince' after 'dee' is 'deevince'.
'deevince' with letters rearranged gives 'EVIDENCE'.
'provide' is the link.
(Other definitions for evidence that I've seen before include "Data" , "Testimony in a court of law" , "Testimony or outward sign" , "Pressing necessity" , "Supporting facts" .)