Notices defective part (7)
I believe the answer is:
section
'part' is the definition.
(synonyms)
'notices defective' is the wordplay.
'defective' indicates anagramming the letters.
'notices' with letters rearranged gives 'SECTION'.
(Other definitions for section that I've seen before include "Subdivision of a newspaper" , "Segment" , "branch" , "Notices (anag)" , "Divide; part" .)