Called Jack over to provide proof of ownership (5,4)
I believe the answer is:
title deed
'proof of ownership' is the definition.
(legal document which might show proof of ownership)
'called jack over' is the wordplay.
'called' becomes 'titled' (similar in meaning).
'jack' becomes 'Dee' (Jack Dee is a comedian).
'over' says the letters should be written in reverse.
'dee' in reverse letter order is 'eed'.
'titled'+'eed'='TITLE-DEED'
'to provide' is the link.
(Other definitions for title deed that I've seen before include "Document establishing legal right to property" , "Document giving legal right of ownership" , "Having proof of ownership" , "Deleted it (anag.)" , "proper document" .)