Return some old film that has shocking treatment (7)
I believe the answer is:
reelect
'return some old' is the definition.
'reelect' can be an answer for 'return' (synonyms). I'm not certain of the 'some old' bit.
'film that has shocking treatment' is the wordplay.
'film' becomes 'reel' (reel is a kind of film).
'that has' means one lot of letters go next to another.
'shocking treatment' becomes 'ect' (electro-convulsive therapy).
'reel'+'ect'='REELECT'
Can you help me to learn more?
(Other definitions for reelect that I've seen before include "Return to seat" , "Return to office" , "Bring to power again" , "Pick again" , "Put in office again" .)