Aimless commercial break (6)
I believe the answer is:
adrift
'aimless' is the definition.
(synonyms)
'commercial break' is the wordplay.
'commercial' becomes 'ad' (abbreviation for advertisement).
'break' becomes 'rift' (rift can mean a break or opening).
'ad'+'rift'='ADRIFT'
(Other definitions for adrift that I've seen before include "Rudderless, astray" , "'Floating without direction, not tied up (6)'" , "out of touch" , "(Of boat) moving out of control" , "'Directionless, floating freely (6)'" .)