Element illuminated with current in buzz (7)
I believe the answer is:
lithium
'element' is the definition.
(lithium is a kind of element)
'illuminated with current in buzz' is the wordplay.
'illuminated' becomes 'lit' (synonyms).
'with' means one lot of letters go next to another.
'current' becomes 'I' (symbol for electric current).
'in' indicates putting letters inside.
'buzz' becomes 'hum' (synonyms).
'i' put inside 'hum' is 'hium'.
'lit'+'hium'='LITHIUM'
(Other definitions for lithium that I've seen before include "Lightest metallic element" , "Light metal element" , "Light metallic element" , "Silver-white metal (symbol: Li)" , "Chemical element (Li), used in batteries" .)