A runabout in the rubbish dump, or in the garden (6)
I believe the answer is:
'in the garden' is the definition.
I can't judge whether this defines the answer.
'a runabout in the rubbish dump' is the wordplay.
'a runabout' becomes 'urn' (I can't explain this - if you can you should give a lot more credence to this answer).
'in the' indicates putting letters inside.
'rubbish dump' becomes 'tip'.
'urn' inserted into 'tip' is 'TURNIP'.
'or' is the link.
Can you help me to learn more?
(Other definitions for turnip that I've seen before include "'Root vegetable, yellow or white (6)'" , "Fleshy edible white or yellow root" , "veggie" , "Root vegetable of the mustard family" , "Globular food plant" .)