Figure reportedly plump, that lady's ancestor (10)

I believe the answer is:

forefather

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'ancestor' is the definition.
(I know that forefather is a type of ancestor)

'figure reportedly plump that lady's' is the wordplay.
'figure reportedly' becomes 'fore' (I can't justify this - if you can you should believe this answer much more).
'plump' becomes 'fat' (similar in meaning).
'that lady' becomes 'her' (her refers to a woman).
'fore'+'fat'+'her'='FOREFATHER'

Can you help me to learn more?

(Another definition for forefather that I've seen is " Hamlet's rude ancestor".)

I've seen this clue in The Telegraph.

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