Master controls outside body perhaps (7)
I believe the answer is:
remains
'body perhaps' is the definition.
'remains' can be an answer for 'body' (I've seen this before). I'm not sure about the 'perhaps' bit.
'master controls outside' is the wordplay.
'master' becomes 'ma' (Master of Arts).
'controls' becomes 'reins' (take the reins).
'outside' means one lot of letters goes inside another (some letters go outside others).
'ma' placed within 'reins' is 'REMAINS'.
Can you help me to learn more?
(Other definitions for remains that I've seen before include "The body: endures" , "Stays behind" , "surviving old parts" , "Corpse; relics" , "Archaeological relics" .)