Second Starfleet win -- Klingon's captured (9)
I believe the answer is:
twinkling
'second' is the definition.
(I know that twinkling is a type of second)
'starfleet win klingon's captured' is the wordplay.
'captured' says the answer is hidden in the clue.
'TWINKLING' is hidden within 'starfleet win klingon'.
(Other definitions for twinkling that I've seen before include "How stars appear" , "Bat of an eye" , "Second" , "Shining intermittently" , "Jiffy" .)