Where blood flows to one’s ears ineffectually (2,4)
I believe the answer is:
in vain
'where' is the definition.
Both the answer and definition are adverbs. Perhaps they are linked in a way I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for in vain that I've seen before include "Uselessly, without result" , "Futile" , "Uselessly, without success" , "Uselessly, to no profit" , "Uselessly, without any progress" .)