Groom at inn (6)
I believe the answer is:
ostler
'groom at inn' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ostler that I've seen before include "Horse man" , "ER lost (anag) - former stableman" , "He held the horse at the old inn" , "Horseman at the inn of old" , "Horse minder" .)