Exhausted writer sitting in street (5)
I believe the answer is:
spent
'exhausted' is the definition.
('spent' can be similar in meaning to 'exhausted')
'writer sitting in street' is the wordplay.
'writer' becomes 'pen' (I've seen this before).
'sitting in' means one lot of letters goes inside another.
'street' becomes 'st'.
'pen' going inside 'st' is 'SPENT'.
(Other definitions for spent that I've seen before include "Paid out - finished" , "Burned-out" , "Worn Out, exhausted" , "Splashed out" , "Worn out having paid out money." .)