Beat first cynic (9)
I believe the answer is:
defeatist
'cynic' is the definition.
(thesaurus)
'beat first' is the wordplay.
'beat' becomes 'defeat' (synonyms).
'first' becomes 'ist' (ist resembles dst).
'defeat'+'ist'='DEFEATIST'
(Other definitions for defeatist that I've seen before include "If date set (anag.)" , "One giving in too easily" , "Unnecessarily pessimistic" , "He does not expect to win" , "expecting to fail" .)