Work hard for bighead opening tavern in America with retiring Yank (4,1,3)
I believe the answer is:
bust a gut
'work hard' is the definition.
(I've seen this before)
'tavern in america with retiring yank' is the wordplay.
'tavern in' becomes 'bust' (I can't explain this - if you can you should believe this answer much more).
'america' becomes 'a' (common abbreviation - e.g. in organisation names).
'with' is a charade indicator (letters next to each other).
'retiring' says the letters should be written backwards.
'yank' becomes 'tug' (I've seen this before).
'tug' in reverse letter order is 'gut'.
'bust'+'a'+'gut'='BUST A GUT'
'for bighead opening' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for bust a gut that I've seen before include "Work extra hard to achieve something" , "Really work extra hard" , "Make a huge effort (slang)" , "Try really hard (slang)" , "Strain" .)