Record held by Greg is terrific (8)
I believe the answer is:
register
'record' is the definition.
(register is a kind of record)
'held by greg is terrific' is the wordplay.
'held by' indicates the answer is hidden within the clue.
'REGISTER' is hidden in the letters of 'greg is terrific'.
(Other definitions for register that I've seen before include "Notice < book" , "Greet sir (anag.)" , "Offical roll of names" , "Show" , "New arrival at hotel will" .)