Need to pay some fellow eventually (3)
I believe the answer is:
owe
'need to pay' is the definition.
(I've seen this in another clue)
'some fellow eventually' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'OWE' is hidden within 'fellow eventually'.
(Other definitions for owe that I've seen before include "overdrawn" , "Be indebted" , "Need to pay" , "have favours to return" , "Have outstanding" .)