Is right to leave at the start, when argument turns into a brawl (9)

'a brawl' is the definition.
(I know that fistfight is a type of brawl)

'is right to leave at the start when argument turns' is the wordplay.
I cannot quite understand how this works, but
'is' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

'into' is the link.

Can you help me to learn more?