Hasten to sink (7)
I believe the answer is:
scuttle
I believe this clue is a double definition.
'hasten' is the first definition.
(thesaurus)
'sink' is the second definition.
(to deliberately sink a ship)
'to' acts as a link.
(Other definitions for scuttle that I've seen before include "container carrying coal?" , "Sink one's ship deliberately" , "Sink (one's ship) - coal holder" , "container for nuts" , "Sink with cutlets" .)