Some compete routinely and come to nothing (5,3)
I believe the answer is:
peter out
'come to nothing' is the definition.
(thesaurus)
'some compete routinely and' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'PETER OUT' is hidden within 'compete routinely and'.
(Other definitions for peter out that I've seen before include "Diminish feebly" , "True poet (anag) - come to nothing" , "Dwindle away to nothing" , "Decrease gradually before ending" , "'Run down, taper off (5,3)'" .)