Twins have to come first (3)
I believe the answer is:
win
'come first' is the definition.
(as in coming first in a race)
'twins have' is the wordplay.
'have' indicates the answer is hidden within the clue.
'WIN' is hidden within 'twins'.
'to' acts as a link.
(Other definitions for win that I've seen before include "Achieve victory" , "Gain; triumph" , "Come first" , "Finish in first place" , "Succeed, conquer" .)