Track down last in talent contest (5)
I believe the answer is:
trace
'track down' is the definition.
(thesaurus)
'last in talent contest' is the wordplay.
'last in' says to take the final letters.
'contest' becomes 'race' (race is a kind of contest).
The last letter of 'talent' is 't'.
't'+'race'='TRACE'
(Other definitions for trace that I've seen before include "Vestige, hint" , "Pinch" , "Follow step by step" , "Smidgen" , "Locate by investigation" .)