Fanatic given such sound treatment? (5)
I believe the answer is:
ultra
I believe this clue is a double definition.
'fanatic' is the first definition.
(I've seen this in another clue)
'such sound treatment?' is the second definition.
(I've seen this before)
'given' is the link.
(Other definitions for ultra that I've seen before include "Over the top" , "holding extreme position" , "Fanatic" , "Above, beyond, super" , "(As prefix) beyond or extreme" .)