Apparently, pals begin to play? (6,2)

I believe the answer is:

strike up

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'begin to play?' is the definition.
(as in beginning a piece of music)

I don't understand the remainder of the clue.

(Other definitions for strike up that I've seen before include "Start playing music - begin (acquaintance) - emboss" , "Begin to play (a piece of music)" .)

I've seen this clue in The Telegraph.

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