Bulb working – something positive, possibly (5)
I believe the answer is:
onion
'bulb' is the definition.
(plant bulb)
'working something positive possibly' is the wordplay.
I cannot quite see how this works, but
'working' could be 'on' (e.g. a machine is working or on) and 'on' is found within the answer.
The remaining letters 'ion' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for onion that I've seen before include "Strong tasting vegetable" , "Tear-jerking bulb" , "Cause of tears" , "one understood by expert" , "Plant with edible bulb" .)