Double time and finish in front (4)
I believe the answer is:
twin
'double' is the definition.
(twin can mean someone's double)
'time and finish in front' is the wordplay.
'time' becomes 't' (abbreviation).
'and' is a charade indicator (letters next to each other).
'finish in front' becomes 'win' (eg win a race).
't'+'win'='TWIN'
(Other definitions for twin that I've seen before include "One of two conceived together" , "Identical sibling" , "Castor or Pollux?" , "One of an identical pair" , "One of two born together" .)