Dressing no cub wears out (5,5)
I believe the answer is:
'dressing' is the definition.
(type of sauce or dressing)
'no cub wears out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'nocubwears' with letters rearranged gives 'BROWN SAUCE'.
(Another definition for brown sauce that I've seen is " Relish".)