Every bit of anger is currently in favour (3,3,4)
I believe the answer is:
all the rage
'favour' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I don't see?
'every bit of anger is currently in' is the wordplay.
'every bit of' becomes 'all' (I've seen this in another clue).
'anger' becomes 'rage' (rage is a kind of anger).
'is currently' becomes 'the' (I am not sure about this - if you are sure you should believe this answer much more).
'in' is an insertion indicator.
'all'+'rage'='allrage'
'allrage' enclosing 'the' is 'ALL THE RAGE'.
Can you help me to learn more?
(Other definitions for all the rage that I've seen before include "Very much in fashion" , "Very popular (informal)" , "The in thing" , "ultra-fashionable" , "in vogue?" .)