Become submerged in floods in Kingston (4)
I believe the answer is:
sink
'become submerged' is the definition.
(sink underwater)
'in floods in kingston' is the wordplay.
'in' says the answer is hidden in the clue.
'SINK' is hidden in the letters of 'floods in kingston'.
(Other definitions for sink that I've seen before include "(Cause to) become submerged" , "Decline - in the kitchen" , "Drop N flag" , "Go down (in the kitchen?)" , "Excavate (a well)" .)