Mock female yob (5)
I believe the answer is:
flout
'mock' is the definition.
(I've seen this in another clue)
'female yob' is the wordplay.
'female' becomes 'f' (common abbreviation).
'yob' becomes 'lout' (both can mean an antisocial young man).
'f'+'lout'='FLOUT'
(Other definitions for flout that I've seen before include "Mock" , "Disobey openly and scornfully" , "Show contempt for (the law)" , "Defy (orders etc)" , "Treat with disdain" .)