Give it everything reversing one vessel towards another (4,1,3)
I believe the answer is:
bust a gut
'give it everything' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
(Other definitions for bust a gut that I've seen before include "Give it everything" , "Work extra hard to achieve something" , "Really work extra hard" , "Strain" , "Make a strenuous effort" .)