The right time for fashion (4)
I believe the answer is:
rage
'for fashion' is the definition.
(something all the rage is fashionable)
'the right time' is the wordplay.
'the right' becomes 'r' (abbreviation).
'time' becomes 'age' (an age is a period of time).
'r'+'age'='RAGE'
(Other definitions for rage that I've seen before include "a poetic response to dying light?" , "Fit of anger" , "Temper - fashion" , "storm" , "Fashionable" .)