The old smile after joke's conclusion, look (7)

'look' is the definition.
Both the answer and definition are singular nouns.
Perhaps there's a link between them I don't understand?

'the old smile after joke's conclusion' is the wordplay.
'the old' becomes 'ye' (resembles a historical spelling of 'the').
'smile' becomes 'beam' (beam can mean to smile).
'after' means one lot of letters go next to another.
'conclusion' suggests the final letters.
The last letter of 'joke' is 'e'.
'ye'+'beam'='yebeam'
'yebeam' put after 'e' is 'EYEBEAM'.

Can you help me to learn more?