Diminished, a knight, at last, is resting (5)
I believe the answer is:
bated
'diminished' is the definition.
(I've seen this in another clue)
'a knight at last is resting' is the wordplay.
I cannot really understand how this works, but
'a' is within the answer.
'knight' could be 'bt' and 'bt' is present in the leftover letters.
The remaining letters 'ed' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for bated that I've seen before include "Reduced (referring to breath)" , "Moderated, the breath in anticipation, say" , "With - breath means in great suspense" .)