Food routes Osage and Hopi interchanged (9)
I believe the answer is:
oesophagi
'food routes' is the definition.
Although both the answer and definition are plural nouns, I cannot see how one could define the other.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for oesophagi that I've seen before include "What act as channels" , "inner tubes" , "parts of canals" , "Crops" , "pipes" .)