Watch, say, brief spins (5)
I believe the answer is:
timer
'watch' is the definition.
(thesaurus)
'brief spins' is the wordplay.
'brief' becomes 'remit' (I've seen this before).
'spins' shows that the letters should be reversed in order (I've seen 'spun' mean this).
'remit' written backwards gives 'TIMER'.
'say' acts as a link.
(Other definitions for timer that I've seen before include "Eg, stopwatch" , "Remit for, say, measuring device - or the measurer (5)" , "Recorder of duration" , "Clocklike actuator" , "Watch, for example" .)