Chap swallowing old beef or grouse (4)
I believe the answer is:
moan
'grouse' is the definition.
(I've seen this in another clue)
'chap swallowing old' is the wordplay.
'chap' becomes 'man' (chap can mean a man).
'swallowing' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'man' going around 'o' is 'MOAN'.
'beef or' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for moan that I've seen before include "Complain, groan" , "Complain; rhymes with money lent" , "Bewail" , "Murmur of pain; grumble" , "Complain; mournful sound" .)