Negative publicity jingle? (7)
I believe the answer is:
adverse
'negative' is the definition.
(I've seen this in another clue)
'publicity jingle?' is the wordplay.
'publicity' becomes 'ad' (short for advert).
'jingle?' becomes 'verse' (jingle is a kind of verse).
'ad'+'verse'='ADVERSE'
(Other definitions for adverse that I've seen before include "Unfavourable - red vase (anag)" , "Unfavourable of the week" , "negative result" , "Inimical" , "Evaders being harmful" .)