Slow down — consider putting in time for golf (6)
I believe the answer is:
retard
'slow down' is the definition.
(I know that slow down can be written as retard)
'consider putting in time for golf' is the wordplay.
I cannot quite see how this works, but
'time' could be 'ret' (I've seen this in other clues) and 'ret' is found within the answer.
The remaining letters 'ard' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for retard that I've seen before include "Slow the progress of, delay" , "Hinder progress" , "Delay effect of" , "Keep back, make slow" , "Detain" .)