Hostile to saga not starting on fashionable street (7)
I believe the answer is:
against
'hostile' is the definition.
(thesaurus)
'saga not starting on fashionable street' is the wordplay.
'not starting' means to remove the first letter.
'on' says to put letters next to each other.
'fashionable' becomes 'in' ('in' can be similar in meaning to 'fashionable').
'street' becomes 'st'.
'saga' with its first letter taken off is 'aga'.
'aga'+'in'+'st'='AGAINST'
'to' acts as a link.
(Other definitions for against that I've seen before include "Not favouring" , "on the other side" , "antagonistic" , "In disagreement with" , "Disapproving of" .)