Mark and Jack are the recipients (6)

I believe the answer is:

target

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'mark' is the definition.
(I know this)

'jack are the recipients' is the wordplay.
'jack' becomes 'tar' (both are informal terms for sailor).
'are the recipients' becomes 'get' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'tar'+'get'='TARGET'

'and' is the link.

Can you help me to learn more?

(Other definitions for target that I've seen before include "Aim, objective" , "Something to aim for" , "Object to be attained by archers (or fund raisers?)" , "Object of attack" , "Aimpoint" .)

I've seen this clue in the Evening Standard.

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