Something highway architect might be asked to design in contract (7)
I believe the answer is:
abridge
'contract' is the definition.
('abridge' can be a synonym of 'contract')
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for abridge that I've seen before include "Make shorter in brigade" , "Big read (anag) - shorten text" , "Condense, summarise" , "Make a precis of" , "Shorten (a literary work)" .)