Step showing how feed is fetched (5)
I believe the answer is:
notch
'step' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for notch that I've seen before include "Indentation - step up" , "Small V-shaped cut or indentation" , "Incision; indentation" , "Point or degree in a scale" , "Cleft" .)