Maybe a mini source of advice (3)
I believe the answer is:
cab
'source of advice' is the definition.
(I've seen this in other clues)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for cab that I've seen before include "Organisation to collect money made from crime" , "A taxi in New York" , "Hackney" , "Driver's compartment, in lorry say" , "An American taxi" .)