Is this 'th bst of th bst'? (5)
I believe the answer is:
elite
'is this 'th bst of th bst'?' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for elite that I've seen before include "type in pool?" , "Aristocracy" , "A privileged or select group" , "one of the letter sizes" , "Group considered to have superior status" .)