Crossword Genius

They'll understand setter's intention, if you catch my drift (4,4,1,4)

Ross

I believe the answer is:

know what i mean

I'm a little stuck... Click here to teach me more about this clue!

'intention if you catch my drift' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'they'll understand setter's' is the wordplay.
I cannot quite understand how this works, but
'understand' could be 'know' (I've seen this in another clue) and 'know' is located in the answer.
'setter's' could be 'im' (referring to the person who set the crossword) and 'im' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Irish Times.
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