Old old man (2-7)

I believe the answer is:

ex-husband

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

'old old man' is the definition.
'ex-husband' can be an answer for 'man' (ex-husband is a kind of man). I am not certain of the 'old old' bit.

'old man' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'man' becomes 'husband' (someone's man could mean their husband).
'ex'+'husband'='EX-HUSBAND'

Can you help me to learn more?

I've seen this clue in The Sunday Times.

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