Ultimately lose knight to chess champ's closing moves (6)
I believe the answer is:
ending
'closing moves' is the definition.
'ending' can be an answer for 'closing' (thesaurus). I am unsure of the 'moves' bit.
'ultimately lose knight to chess champ's' is the wordplay.
'ultimately' says to take the final letters.
'knight' becomes 'n' (chess abbreviation).
'to chess champ' becomes 'ding' (I can't justify this - if you can you should give a lot more credence to this answer).
The final letter of 'lose' is 'e'.
'e'+'n'+'ding'='ENDING'
Can you help me to learn more?
(Other definitions for ending that I've seen before include "Close - conclusion" , "ultimately" , "Concluding" , "terminal" , "Finish" .)