Clear the one in the middle of the road (3)
I believe the answer is:
rid
'clear' is the definition.
(synonyms)
'one in the middle of the road' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in the middle of' is an insertion indicator.
'the road' becomes 'rd' (abbreviation).
'i' inserted inside 'rd' is 'RID'.
'the' acts as a link.
(Other definitions for rid that I've seen before include "Disabuse" , "Free, relieve" , "Free from something unpleasant" , "Free, disencumber" , "Free, deliver, clear" .)