The record is between 100 and 500 (4)
I believe the answer is:
disc
'the record' is the definition.
(synonyms)
'is between 100 and 500' is the wordplay.
'between' indicates putting letters inside.
'100' becomes 'c' (roman numeral).
'and' means one lot of letters go next to another (I've seen this in other clues).
'500' becomes 'd' (Roman numeral for 500).
'c' after 'd' is 'dc'.
'is' placed into 'dc' is 'DISC'.
(Other definitions for disc that I've seen before include "Back part" , "something moving in the spine" , "Flat thin circular body" , "Spine cartilage layer" , "Flat round plate" .)