The record is held by the District of Columbia (4)
I believe the answer is:
disc
'the record' is the definition.
(eg a CD, compact disc)
'is held by the district of columbia' is the wordplay.
'held by' means one lot of letters goes inside another.
'the district of columbia' becomes 'DC' (synonyms).
'is' inserted into 'dc' is 'DISC'.
(Other definitions for disc that I've seen before include "45, eg?" , "Old record" , "something moving in the spine" , "Sound recording" , "Protein-constituent acid" .)