Cut GP mentioned (4)
I believe the answer is:
dock
'cut' is the definition.
(docking is a kind of cutting)
'gp mentioned' is the wordplay.
'gp' becomes 'doc' (I've seen this in other clues).
'mentioned' indicates a 'sounds like' (homophone) clue.
'doc' is a homophone of 'DOCK'.
(Other definitions for dock that I've seen before include "land" , "Deduct (from wages)" , "Cut short; place for defendant" , "Stop (from pay); sting-soothing plant" , "Berthing area; cut" .)