Produce I'd demonstrate about (7)
I believe the answer is:
provide
'produce' is the definition.
(thesaurus)
'i'd demonstrate about' is the wordplay.
'demonstrate' becomes 'prove' (synonyms).
'about' indicates putting letters inside.
'id' placed within 'prove' is 'PROVIDE'.
(Other definitions for provide that I've seen before include "'Furnish, supply (7)'" , "PR video (anag.)" , "Make available, supply" .)