One's covering trade standards (6)
I believe the answer is:
ideals
'standards' is the definition.
(I have seen 'High standards ' mean 'ideals' so perhaps 'standards' could also mean 'ideals')
'one's covering trade' is the wordplay.
'one's' becomes 'is' (roman numeral).
'covering' indicates putting letters inside.
'trade' becomes 'deal' ('deal' can be a synonym of 'trade').
'is' enclosing 'deal' is 'IDEALS'.
(Other definitions for ideals that I've seen before include "Standards to aim for" , "Models of excellence" , "Models of excellance" , "Dreams" , "Lofty aspirations for ladies" .)