Popeye's girl in green (5)
I believe the answer is:
olive
I believe this is a double definition.
'popeye's girl' is the first definition.
(I've seen this in another clue)
'green' is the second definition.
(olive green is a kind of green)
'in' acts as a link.
(Other definitions for olive that I've seen before include "Girl's name; tree" , "Type of green" , "This branch is offered to show peace" , "Yellowish-green colour" , "Oil-yielding fruit" .)