Assault and hold expert (3,4)

I believe the answer is:

old hand

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'expert' is the definition.
(old hand is a kind of expert)

'assault and hold' is the wordplay.
'and hold' can be anagrammed to 'OLD HAND'.
Though, I am unsure how this is indicated.

Can you help me to learn more?

(Other definitions for old hand that I've seen before include "One that's experienced" , "Veteran" , "mediaeval script" , "Experience or well-practised person" , "Experienced or practised person - manually aged?" .)

I've seen this clue in the Sydney Morning Herald.

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