Supply identification inside show (7)
I believe the answer is:
provide
'supply' is the definition.
(I know that supply can be written as provide)
'identification inside show' is the wordplay.
'identification' becomes 'ID' (abbreviation).
'inside' indicates putting letters inside.
'show' becomes 'prove' (synonyms).
'id' placed inside 'prove' is 'PROVIDE'.
(Other definitions for provide that I've seen before include "PR video (anag.)" , "Make available, supply" , "'Furnish, supply (7)'" .)