Hack back old-fashioned, short frizzy hairdo (8)
I believe the answer is:
reporter
'hack' is the definition.
(informal term for a journalist)
'back old-fashioned short frizzy hairdo' is the wordplay.
'back' is a reversal indicator.
'old-fashioned' becomes 'retro' (I've seen this before).
'short' means to remove the last letter.
'frizzy hairdo' becomes 'perm'.
'perm' with its last letter taken away is 'per'.
'retro'+'per'='retroper'
'retroper' back-to-front is 'REPORTER'.
(Other definitions for reporter that I've seen before include "Collector of news for media" , "Newspaper worker" , "He gives details" , "One writes or tells the news" , "Journo" .)