Element in benefit about right (5)
I believe the answer is:
boron
'element' is the definition.
(I know that boron is a type of metalloid)
'benefit about right' is the wordplay.
'benefit' becomes 'boon' (a boon is a help or benefit).
'about' is an insertion indicator.
'right' becomes 'r' (common abbreviation).
'boon' placed around 'r' is 'BORON'.
'in' is the link.
(Other definitions for boron that I've seen before include "component of steel" , "Atomic no 5" , "Metalloid element, B" , "Non-metallic element, symbol B" , "Chemical element, symbol B" .)