Make for the gun in the coloured holster (7)
I believe the answer is:
produce
'make' is the definition.
(synonyms)
'gun in the coloured holster' is the wordplay.
'gun' becomes 'rod' (rod is a kind of gun).
'in the' means one lot of letters goes inside another.
'coloured holster' becomes 'puce' (I can't explain this - if you can you should give a lot more credence to this answer).
'rod' placed inside 'puce' is 'PRODUCE'.
'for the' is the link.
Can you help me to learn more?
(Other definitions for produce that I've seen before include "Bear" , "Fresh fruit and veg for market - crop due (anag)" , "Create - crop" , "Create, manufacture" , "Make, manufacture" .)