Unfashionable co-star's jacket, at the end of the day, results in widespread disapproval (6)
I believe the answer is:
outcry
'widespread disapproval' is the definition.
'outcry' can be an answer for 'disapproval' (I have seen 'Public disapproval ' mean 'outcry' so perhaps 'disapproval' could also mean 'outcry'). I am unsure of the 'widespread' bit.
'unfashionable co-star's jacket at the end of the day' is the wordplay.
'unfashionable' becomes 'out' (synonyms).
'co-star's jacket' becomes 'cr' (I am not sure about this - if you are sure you should believe this answer much more).
'at the end of' indicates one should take the final letters.
The final letter of 'day' is 'y'.
'out'+'cr'+'y'='OUTCRY'
'results in' acts as a link.
Can you help me to learn more?
(Other definitions for outcry that I've seen before include "Public show of anger" , "A storm of protest" , "commotion" , "Exclamation - clamour" , "Exclamations of opposition" .)