Aimless publicity break (6)
I believe the answer is:
adrift
'aimless' is the definition.
(synonyms)
'publicity break' is the wordplay.
'publicity' becomes 'ad' (advert).
'break' becomes 'rift' (I've seen this before).
'ad'+'rift'='ADRIFT'
(Other definitions for adrift that I've seen before include "Not anchored, floating freely" , "Disoriented" , "Purposeless" , "Wandering aimlessly" , "Floating freely, not moored" .)