Injurious commercial, very Irish (7)
I believe the answer is:
adverse
'injurious' is the definition.
(thesaurus)
'commercial very irish' is the wordplay.
'commercial' becomes 'ad'.
'very' becomes 'v' (abbreviation).
'irish' becomes 'erse' (I've seen this before).
'ad'+'v'+'erse'='ADVERSE'
(Other definitions for adverse that I've seen before include "In an opposing direction" , "Conflicting" , "Inimical" , "negative result" , "Opposed to or unfavourable" .)