Mine's best chance to refuel (3,4)
I believe the answer is:
pit stop
'chance to refuel' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'mine's best' is the wordplay.
'mine's' becomes 'pit's' (down the pit).
'best' becomes 'top' (top can mean the very best).
'pits'+'top'='PIT STOP'
Can you help me to learn more?
(Other definitions for pit stop that I've seen before include "When tripping, break" , "period of service?" , "for rest of travellers" , "Break for fuel etc." , "Break during motor race" .)