A source of cash keeps personnel excited (7)

I believe the answer is:

athrill

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'excited' is the definition.
Both the definition and answer are adjectives.
Maybe you can see a link between them that I don't see?

'a source of cash keeps personnel' is the wordplay.
'source of cash' becomes 'till' (I can't justify this - if you can you should believe this answer much more).
'keeps' means one lot of letters goes inside another (inserted letters are kept inside).
'personnel' becomes 'HR' (Human Resources).
'till' placed around 'hr' is 'thrill'.
'a'+'thrill'='ATHRILL'

Can you help me to learn more?

I've seen this clue in The Independent.

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