Bulb working with charged particle (5)
I believe the answer is:
onion
'bulb' is the definition.
(plant bulb)
'working with charged particle' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'with' says to put letters next to each other.
'charged particle' becomes 'ion' (I've seen this in another clue).
'on'+'ion'='ONION'
(Other definitions for onion that I've seen before include "Pungent edible bulb of the lily family" , "Bulb used as a vegetable" , "Alliaceous plant" , "Bulb used in cooking" , "one understood by expert" .)