Picks different teams and transfers one's loyalties (7,5)

I believe the answer is:

filling yarns

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

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

'different teams and transfers one's loyalties' is the wordplay.
I cannot really understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is found in the answer.
'one' could be 'li' (I've seen this in other clues) and 'li' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Irish Independent.

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