Some suggest I’m a terrible judge (8)
I believe the answer is:
estimate
'judge' is the definition.
(I know that judge can be written as estimate)
'some suggest i'm a terrible' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'ESTIMATE' can be found hidden inside 'suggest im a terrible'.
(Other definitions for estimate that I've seen before include "Make an educated guess" , "Judgment, appraisal" , "Guess the cost" , "Likely amount" , "Evaluate - approximation" .)