Notices different part (7)
I believe the answer is:
section
'part' is the definition.
(I know that part can be written as section)
'notices different' is the wordplay.
'different' indicates an anagram (letters placed in a different order).
'notices' anagrammed gives 'SECTION'.
(Other definitions for section that I've seen before include "Department, division" , "Subdivision of a newspaper" , "Divide; part" , "Distinct part" , "branch" .)