Element of Northern Ireland I instilled in old tramp (7)
I believe the answer is:
niobium
'element' is the definition.
(I know that niobium is a type of metal)
'northern ireland i instilled in old tramp' is the wordplay.
'northern ireland' becomes 'NI' (abbreviation).
'instilled in' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'tramp' becomes 'bum' (both can mean a homeless person).
'o'+'bum'='obum'
'i' going into 'obum' is 'obium'.
'ni'+'obium'='NIOBIUM'
'of' acts as a link.
(Other definitions for niobium that I've seen before include "Silver-grey metallic element" , "Silver-grey metal, Nb" , "Superconductive element" , "Chemical element, Nb" , "Silvery-grey metal, Nb" .)