Standard cut reduced (3)
I believe the answer is:
'standard' is the definition.
(I've seen this before)
'cut reduced' is the wordplay.
'cut' becomes 'pare' (paring is a kind of cutting).
'reduced' means to remove the last letter.
'pare' with its final letter removed is 'PAR'.
(Other definitions for par that I've seen before include "Normal golfing score", "Rating of strokes required for hole (golf)", "Standard amount", "standard for course", "normal amount".)