Notice poetry's detrimental (7)
I believe the answer is:
adverse
'detrimental' is the definition.
(I've seen this in another clue)
'notice poetry's' is the wordplay.
'notice' becomes 'ad' (both can mean an advertisement).
'poetry' becomes 'verse' (synonyms).
'ad'+'verse'='ADVERSE'
(Other definitions for adverse that I've seen before include "Hostile" , "Unfavourable - red vase (anag)" , "Evaders being harmful" , "Dire" , "Unfavourable or harmful, perhaps criticism" .)