In touch certainly and holding one's share of the deal (4-2-4)

I believe the answer is:

hand-in-hand

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'in touch certainly and holding one's' is the definition.
I know nothing about this answer so I can't tell whether this works.

'share of the deal' is the wordplay.
'share of' becomes 'handin' (I can't explain this - if you can you should give a lot more credence to this answer).
'the deal' becomes 'hand' ('hand' can be a synonym of 'deal').
'handin'+'hand'='HAND-IN-HAND'

Can you help me to learn more?

(Another definition for hand-in-hand that I've seen is " Jointly".)

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

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