Best at everything, including standing (6)
I believe the answer is:
estate
'standing' is the definition.
(thesaurus)
'best at everything including' is the wordplay.
'including' says the answer is hidden in the clue.
'ESTATE' is hidden in the letters of 'best at everything'.
(Other definitions for estate that I've seen before include "Property - tea set (anag)" , "One car" , "Possessions at the time of death" , "Industrial area" , "Car with big luggage area" .)