Obsessive over new record (5)
I believe the answer is:
annal
'record' is the definition.
(I've seen this before)
'obsessive over new' is the wordplay.
'obsessive' becomes 'anal' (I've seen this before).
'over' is an insertion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'anal' enclosing 'n' is 'ANNAL'.
(Other definitions for annal that I've seen before include "Recorded events of a year" , "record shows" , "Record of one year" , "Record of a year's events" , "Year's entry in chronicle" .)