Fashionable scoundrel split (7)
I believe the answer is:
current
'fashionable' is the definition.
(thesaurus)
'scoundrel split' is the wordplay.
'scoundrel' becomes 'cur' (cur can mean a despicable person).
'split' becomes 'rent' (past tense of 'rend' meaning to split).
'cur'+'rent'='CURRENT'
(Other definitions for current that I've seen before include "Flow of electricity" , "Electrical flow" , "Stream - in the news" , "Contemporary" , "In vogue" .)