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