The most common and most likely answer to this crossword clue is the 6 letter word MEDLEY
I've seen this crossword clue in The Guardian
M
E
D
L
E
Y
More clues leading to the result MEDLEY
Buddy explains!

The straight part
We know that "tunes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tunes = medley.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does MEDLEY mean?
MEDLEY noun- Combat, fighting; a battle.
- A collection or mixture of miscellaneous things.
- A collection of related songs played or mixed together as a single piece.
- A competitive swimming event that combines the four strokes of butterfly, backstroke, breaststroke, and freestyle.
- A cloth of mixed colours.
- To combine, to form a medley.