Plug more fitting for plug attachment (7)
I believe the answer is:
adapter
'plug attachment' is the definition.
(I've seen this before)
'plug more fitting' is the wordplay.
'plug' becomes 'ad' (as in plugging a product).
'more fitting' becomes 'apter' (I've seen this in another clue).
'ad'+'apter'='ADAPTER'
'for' is the link.
(Other definitions for adapter that I've seen before include "Dear Pat (anag)" , "sort of plug" , "I could modify" , "Plug attachment" , "'Apt, dear!' (anag.); a switching device" .)