Mean to add to the quarter yard (4)
I believe the answer is:
spar
'yard' is the definition.
(I've seen this in another clue)
'mean to add to the quarter' is the wordplay.
'mean' becomes 'par' (average score on a golf course).
'to add to' is a charade indicator (letters next to each other).
'the quarter' becomes 's'.
'par' put after 's' is 'SPAR'.
(Other definitions for spar that I've seen before include "Shadow box" , "Box gently; main beam of aircraft wing" , "Length of wood" , "possibly rigged" , "Box in training - nautical pole" .)