New missile contract (6)
I believe the answer is:
narrow
'contract' is the definition.
('narrow' can be a synonym of 'contract')
'new missile' is the wordplay.
'new' becomes 'n'.
'missile' becomes 'arrow' (arrow is a kind of missile).
'n'+'arrow'='NARROW'
(Other definitions for narrow that I've seen before include "Limited in scope; not wide" , "Bigoted opinion" , "Strait, not wide" , "Strait or thin" , "Strict" .)