Secretariat holds this back from judge (4)
I believe the answer is:
rate
'judge' is the definition.
(rating is a kind of judging)
'secretariat holds this back from' is the wordplay.
'from' indicates a hidden word.
'this back' is a reversal indicator.
'etar' can be found hidden inside 'secretariat holds'.
'etar' in reverse letter order is 'RATE'.
(Other definitions for rate that I've seen before include "Charge per unit" , "quality" , "Tariff" , "Price - class - speed" , "The price paid" .)