Exhausted writer found in the road (5)
I believe the answer is:
spent
'exhausted' is the definition.
('spent' can be similar in meaning to 'exhausted')
'writer found in the road' is the wordplay.
'writer' becomes 'pen' (I've seen this before).
'found in' indicates putting letters inside.
'the road' becomes 'st'.
'pen' placed inside 'st' is 'SPENT'.
(Other definitions for spent that I've seen before include "Drained of energy - or paid out" , "Exhausted, having paid money?" , "Expended" , "Worn Out, exhausted" , "Worn out having paid out money." .)