Lost without commercial break (4)
I believe the answer is:
rift
'break' is the definition.
(thesaurus)
'lost without commercial' is the wordplay.
'lost' becomes 'adrift'.
'without' suggests deleting specific letters.
'commercial' becomes 'ad'.
'adrift' with 'ad' taken out is 'RIFT'.
(Other definitions for rift that I've seen before include "Breach, rupture" , "Cleft in rock" , "Breach - falling-out" , "Serious falling out" , "opening" .)