Useful item, suitable in road construction (7)
I believe the answer is:
adaptor
'useful item' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'suitable in road construction' is the wordplay.
'suitable' becomes 'apt' (apt means appropriate or fitting).
'in' is an insertion indicator.
'construction' indicates anagramming the letters (answer constructed from certain letters).
'road' with letters rearranged gives 'ador'.
'apt' going into 'ador' is 'ADAPTOR'.
Can you help me to learn more?
(Other definitions for adaptor that I've seen before include "Tap road (anag)" , "Connector (O, not E)" , "Kind of electric plug" , "Device that enables more than one plug per socket" , "It enables fit" .)