Mad hairstyle for fanatics (7,6)
I believe the answer is:
lunatic fringe
'fanatics' is the definition.
(I have seen 'Political fanatics' mean 'lunatic fringe' so perhaps 'fanatics' could also mean 'lunatic fringe')
'mad hairstyle' is the wordplay.
'mad' becomes 'lunatic' (I've seen this before).
'hairstyle' becomes 'fringe' ().
'lunatic'+'fringe'='LUNATIC FRINGE'
'for' is the link.
(Other definitions for lunatic fringe that I've seen before include "Political fanatics" , "Extreme political element" , "Fanatical element" , "Barmy extremists" , "Extreme fanatics" .)