Other obstinate knight’s refusal to drink (10)
I believe the answer is:
abstention
'refusal to drink' is the definition.
I can't tell whether this defines the answer.
'other obstinate knight's' is the wordplay.
'other' indicates anagramming the letters.
'knight' becomes 'n' (chess abbreviation).
'obstinate' anagrammed gives 'abstentio'.
'abstentio'+'n'='ABSTENTION'
Can you help me to learn more?
(Other definitions for abstention that I've seen before include "Act of declining to vote" , "endorsing no candidate" , "Withholding of vote" , "forbearance" , "Sitting on fence" .)