Records terrible slog (4)
I believe the answer is:
logs
'records' is the definition.
(logging is a kind of recording)
'terrible slog' is the wordplay.
'terrible' is an anagram indicator.
'slog' with letters rearranged gives 'LOGS'.
(Other definitions for logs that I've seen before include "Written records of events on board" , "Written record of a voyage" , "Firewood; records" .)