Scold horse (3)
I believe the answer is:
nag
This clue is a double definition.
'scold' is the first definition.
(I know that scold can be written as nag)
'horse' is the second definition.
(term for an old horse)
(Other definitions for nag that I've seen before include "Scold like an old horse" , "Scold persistently, annoy" , "Harry" , "Badger continually like old horse" , "Badger with constant complaints" .)