Most rowdy sporting tunes include game by line one (9)
I believe the answer is:
Here is my best explanation:
'most rowdy' is the definition.
'sporting tunes include game by line one' is the subsidiary indication.
I cannot really see how this works, but
'game' could be 'ru' (rugby union) and 'ru' is present in the answer.
an anagram of 'line' is 'nlie' which is present in the remaining letters.
This may be the basis of clue (or it may be nonsense).
(Another definition for unruliest that I've seen is "Most disobedient".)