It’s Irish coming back following catastrophic start with epic finish for commentator (6)
I believe the answer is:
critic
'for commentator' is the definition.
(thesaurus)
'it's irish coming back following catastrophic start with epic finish' is the wordplay.
'irish' becomes 'IR' (abbreviation).
'coming back' is a reversal indicator.
'following' means one lot of letters go next to another.
'start with' indicates taking the first letters.
'finish' suggests the final letters.
The first letter of 'catastrophic' is 'c'.
The last letter of 'epic' is 'c'.
'it'+'ir'='itir'
'itir' back-to-front is 'riti'.
'riti' after 'c' is 'criti'.
'criti'+'c'='CRITIC'
(Other definitions for critic that I've seen before include "(Eg, theatre) reviewer" , "One analyses and interprets works of art" , "One judges the merit of artistic works" , "Arts reviewer" , "Newspaper reviewer" .)