Grumpy person, resident doubling up at the outset (6)

I believe the answer is:

codger

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'grumpy person' is the definition.
'codger' can be an answer for 'person' (codger is a kind of person). I am unsure of the 'grumpy' bit.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for codger that I've seen before include "Old bloke" , "Old and eccentric chap" , "Old person" , "(Old) man" , "fellow" .)

I've seen this clue in The Telegraph.

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