Lithium company beset by wrong element (7)
I believe the answer is:
silicon
'element' is the definition.
(I know that silicon is a type of element)
'lithium company beset by wrong' is the wordplay.
'lithium' becomes 'Li' (Li is the chemical symbol for lithium).
'company' becomes 'co' (abbreviation).
'beset by' is an insertion indicator ('beset' could historically mean 'cover').
'wrong' becomes 'sin' (wrong can mean a sin or crime).
'li'+'co'='lico'
'lico' placed inside 'sin' is 'SILICON'.
(Other definitions for silicon that I've seen before include "Semi-conducting non-metal" , "Element found in chips?" , "Element used in integrated circuits" , "Element used in electronic circuits" , "Computer chip element" .)