Look-alike (6)
I believe the answer is:
double
'look-alike' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for double that I've seen before include "Twice the amount" , "Twice - bent over - run" , "Second charge for the same offence" , "Person who says one thing and does another" , "Dartboard outer score" .)