Find missing past record (4)
I believe the answer is:
disc
'record' is the definition.
('disc' can be a synonym of 'record')
'find missing past' is the wordplay.
'find' becomes 'discover' ('discover' can be a synonym of 'find').
'missing' indicates named letters should be taken away.
'past' becomes 'over' (I've seen this before).
'discover' with 'over' taken away is 'DISC'.
(Other definitions for disc that I've seen before include "Flat thin round object" , "Circular flat structure in the spine" , "45, eg?" , "'Round, flat shape (4)'" , "Body without limbs" .)