Underdog troubles United coaches (7,6)

I believe the answer is:

outside chance

I'm a little stuck... Click here to teach me more about this clue!

'underdog' is the definition.
I know nothing about this answer so I can't judge whether this works.

'troubles united coaches' is the wordplay.
'troubles' indicates an anagram (I've seen 'trouble' mean this).
'united'+'coaches'='unitedcoaches'
'unitedcoaches' is an anagram of 'OUTSIDE CHANCE'.

Can you help me to learn more?

(Other definitions for outside chance that I've seen before include "It might just happen" , "one at long odds" , "smallest likelihood" .)

I've seen this clue in the Sydney Morning Herald.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.