Unconventional lad, tho’ far from fashionable (3,3)
I believe the answer is:
Here is my best explanation:
'far from fashionable' is the definition.
'unconventional lad tho'' is the subsidiary indication.
'unconventional' indicates an anagram.
'ladtho' is an anagram of 'oldhat'.
(Other definitions for old hat that I've seen before include "Boringly familiar", "Shabby cover", "Tediously familiar or outdated, like obsolete headgear", "not the gear for Ascot?", "Passe", "Ancient headgear is out of fashion", "Tediously familiar like ancient headgear", "Out of fashion, like ancient headgear", "A tediously familiar thing" and "Antediluvian".)