National insurance's introduction is real variable (7)
I believe the answer is:
israeli
'national' is the definition.
(someone from Israel)
'insurance's introduction is real variable' is the wordplay.
'introduction' indicates taking the first letters.
'variable' indicates anagramming the letters (a varied form of the letters).
The first letter of 'insurances' is 'i'.
'is'+'real'='isreal'
'isreal' with letters rearranged gives 'sraeli'.
'i'+'sraeli'='ISRAELI'
(Other definitions for israeli that I've seen before include "Faithful inhabitant" , "See member of modern state" , "Citizen of a Middle Eastern nation" , "A Middle-Easterner" , "As national of modern republic" .)