Last word in hairstyles, fashionable (7,4)
I believe the answer is:
parting shot
'last word' is the definition.
(thesaurus)
'hairstyles fashionable' is the wordplay.
'hairstyles' becomes 'partings' (I can't justify this - if you can you should give a lot more credence to this answer).
'fashionable' becomes 'hot' (hot can mean fashionable or trendy).
'partings'+'hot'='PARTING SHOT'
'in' acts as a link.
Can you help me to learn more?
(Another definition for parting shot that I've seen is " Cutting remark on leaving".)