Call it a day having received medal and diamonds (2,2,3)
I believe the answer is:
go to bed
'call it a day' is the definition.
I can't tell whether this defines the answer.
'received medal and diamonds' is the wordplay.
'received' becomes 'got' ('get' can be a synonym of 'receive').
'medal' becomes 'OBE' (Order of the British Empire).
'and' means one lot of letters go next to another.
'diamonds' becomes 'd' (abbreviation in bridge say).
'got'+'obe'+'d'='GO TO BED'
'having' acts as a link.
Can you help me to learn more?
(Another definition for go to bed that I've seen is " Retire".)