Tees buys the beers for a song (1,3,6)

'tees buys the beers' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'a song' is the wordplay.
I cannot quite understand how this works, but
'a' is found in the answer.
'song' could be 'round' (round is a kind of song) and 'round' is found in the answer.
This explanation may well be incorrect...

'for' acts as a link.