Poet sounds exhausted (5)
I believe the answer is:
donne
'poet' is the definition.
(16th- and 17th- century poet John Donne)
'sounds exhausted' is the wordplay.
'sounds' indicates a 'sounds like' (homophone) clue.
'exhausted' becomes 'done' (I've seen this in another clue).
'done' sounds like 'DONNE'.
(Other definitions for donne that I've seen before include "Writer of poetry" , "John -, English poet" , "English preacher and metaphysical poet, d. 1631" , "basic assumption" .)