Becomes more cheerful when delegate returns to Kenyan capital to eat (5,2)

I believe the answer is:

perks up

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'becomes more cheerful when delegate returns' is the definition.
I can't tell whether this defines the answer.

'kenyan capital to eat' is the wordplay.
'kenyan capital' becomes 'perk' (I can't justify this - if you can you should believe this answer much more).
'to eat' becomes 'sup' (supping is a kind of eating).
'perk'+'sup'='PERKS UP'

'to' acts as a link.

Can you help me to learn more?

(Another definition for perks up that I've seen is " Enlivens".)

I've seen this clue in The Irish Times.

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