Busy bee left wet mud for plant (10)
I believe the answer is:
tumbleweed
'busy bee left' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'wet mud for plant' is the wordplay.
'wet mud for' becomes 'tumble' (I can't explain this - if you can you should believe this answer much more).
'plant' becomes 'weed' (A weed is a plant).
'tumble'+'weed'='TUMBLEWEED'
Can you help me to learn more?
(Other definitions for tumbleweed that I've seen before include "Western drifter" , "Ball-like remains of plant blown by prairie winds" , "Plant swept along by the wind - wet Elbe mud (anag)" , "Plant of arid regions, rolled about by the wind" , "Plant blown as a dry ball by the wind" .)