Something to keep aunty in change (7)

I believe the answer is:

annuity

I'm a little stuck... Click here to teach me more about this clue!

'something to keep' is the definition.
I can't tell whether this defines the answer.

'aunty in change' is the wordplay.
'change' indicates anagramming the letters.
'aunty'+'in'='auntyin'
'auntyin' anagrammed gives 'ANNUITY'.

Can you help me to learn more?

(Other definitions for annuity that I've seen before include "Form of investment" , "guaranteed payment" , "Sum paid yearly" , "Regular income from a fund" , "Pension income" .)

I've seen this clue in The Globe and Mail.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.