Get rid of one’s vehicle - being collected by daughters (7)
I believe the answer is:
'get rid of' is the definition.
(discarding is a kind of getting rid of)
'one's vehicle being collected by daughters' is the wordplay.
'one's' becomes 'is' (Roman numeral).
'vehicle' becomes 'card' (I can't explain this - if you can you should give a lot more credence to this answer).
'being collected by' says to put letters next to each other (I've seen this in other clues).
'daughters' becomes 'd'.
'iscard' put after 'd' is 'DISCARD'.
Can you help me to learn more?
(Other definitions for discard that I've seen before include "Abandon" , "Shed" , "Get rid of" , "Reject" , "Throw away or cast off" .)