Grant's successor (5)
I believe the answer is:
hayes
'grant's successor' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hayes that I've seen before include "Location in Middlesex" , "part of London" , "Place in Middlesex" , "Former US President" , "West London town; ah, yes (anag.)" .)