Unlikely success getting back from Innsbruck in girl's three-wheeler (5,6)

'unlikely success' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'back from innsbruck in girl's three-wheeler' is the wordplay.
'back from' suggests the final letters (the letter at the back of the word).
'in' indicates putting letters inside.
'girl's' becomes 'Lucy's' (girl's name).
'three-wheeler' becomes 'trike' (tricycle).
The final letter of 'innsbruck' is 'k'.
'k' going inside 'lucys' is 'luckys'.
'luckys'+'trike'='LUCKY STRIKE'

'getting' acts as a link.

Can you help me to learn more?