Unassertive person moving to road round motorway (7)
I believe the answer is:
doormat
'unassertive person' is the definition.
(I know that doormat is a type of unassertive person)
'moving to road round motorway' is the wordplay.
'moving' is an anagram indicator (letters are moved around).
'round' indicates putting letters inside.
'motorway' becomes 'M' (as in motorway names - M1, M4 etc).
'to'+'road'='toroad'
'toroad' is an anagram of 'doorat'.
'doorat' enclosing 'm' is 'DOORMAT'.
(Other definitions for doormat that I've seen before include "Mad root (anag.)" , "Badly treated but uncomplaining person" , "Shoe wiper at entrance" , "Submissive person; shoe cleaner" , "Wipe feet on this before entering" .)