Permitted degree of subtlety (3)
I believe the answer is:
let
'permitted degree' is the definition.
'let' can be an answer for 'permitted' (I've seen this before). I'm not certain of the 'degree' bit.
'of subtlety' is the wordplay.
'of' indicates the answer is hidden within the clue.
'LET' can be found hidden inside 'subtlety'.
Can you help me to learn more?
(Other definitions for let that I've seen before include "Permit or rent" , "Won't stop you" , "& 15 Triple (anag.)" , "Reason for scrubbing service" , "Umpire's decision" .)