Swallow up or submerge (6)
I believe the answer is:
engulf
This clue is a double definition.
'swallow up' is the first definition.
(I've seen this in another clue)
'submerge' is the second definition.
(I've seen this in another clue)
(Other definitions for engulf that I've seen before include "Bury" , "Overwhelm; cover totally" , "Swallow up like wave" , "Swamp, overwhelm" , "Completely overwhelm" .)