Is Nico confused about Latin? Si (7)
I believe the answer is:
silicon
'si' is the definition.
('silicon' can be a synonym of 'si')
'is nico confused about latin?' is the wordplay.
'confused' is an anagram indicator.
'about' is an insertion indicator.
'latin?' becomes 'l'.
'is'+'nico'='isnico'
'isnico' is an anagram of 'siicon'.
'siicon' enclosing 'l' is 'SILICON'.
(Other definitions for silicon that I've seen before include "Non-metallic element, symbol Si" , "Semi-conducting non-metal" , "Computer chip element" , "Non-metallic element with atomic no. 14" , "Element used in integrated circuits" .)