Greenback covered missile contract (6)
I believe the answer is:
narrow
'contract' is the definition.
(synonyms)
'greenback covered missile' is the wordplay.
I cannot really see how this works, but
'missile' could be 'arrow' (arrow is a kind of missile) and 'arrow' is present in the answer.
A single letter 'n' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for narrow that I've seen before include "with little to spare" , "Meagre, confined" , "Slender - spare" , "Vessel designed for canals" , "Of small width, strait" .)