Either way, note clear doctrine (5)
I believe the answer is:
tenet
'either way' is the definition.
'note clear doctrine' is the wordplay.
I cannot really see how this works, but
'note' could be 'te' (musical note) and 'te' is found within the answer.
'clear' could be 'net' (as in net profit) and 'net' is found in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
(Other definitions for tenet that I've seen before include "A belief or credo - it's a palindrome" , "Matter of belief" , "Belief - maxim" , "Article of belief" , "Item of belief" .)