Group of conductors, mostly penniless (3)
I believe the answer is:
bus
'group of conductors' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'mostly penniless' is the wordplay.
'mostly' means to remove the last letter (most but not all of the word).
'penniless' becomes 'bust' (I've seen this before).
'bust' with its last letter taken away is 'BUS'.
Can you help me to learn more?
(Other definitions for bus that I've seen before include "Means of public transport" , "Use transport" , "People carrier" , "eg Double-decker" , "Large passenger vehicle - small business!" .)