Alternative healer's residence on old road (9)
I believe the answer is:
homeopath
'alternative healer's' is the definition.
(homeopathy is alternative medicine)
'residence on old road' is the wordplay.
'residence' becomes 'home' (home is a kind of residence).
'on' means one lot of letters go next to another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'road' becomes 'path'.
'home'+'o'+'path'='HOMEOPATH'
(Other definitions for homeopath that I've seen before include "one offers treatment" , "Quack perhaps" , "therapist" , "Alternative practitioner" , "he treats you, naturally" .)