Coach at game wants duty, heart, toil! (4,1,3)
I believe the answer is:
bust a gut
'duty heart toil' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'coach at game' is the wordplay.
I cannot really see how this works, but
'coach' could be 'bus' (synonyms) and 'bus' is present in the answer.
'game' could be 'tag' (children's playground game) and 'tag' is found in the answer.
The remaining letters 'ut' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'wants' is the link.
Can you help me to learn more?
(Other definitions for bust a gut that I've seen before include "Strain" , "Make a huge effort (slang)" , "Work extra hard to achieve something" , "Really work extra hard" , "Give it everything" .)