Craving hit with a low blow to ear (4)
I believe the answer is:
need
'craving' is the definition.
(I've seen this in another clue)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for need that I've seen before include "Shortage" , "Desideratum" , "Penury" , "state requiring relief" , "Require (as essential)" .)