Constrained to send back an import (4)
I believe the answer is:
edam
'import' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for edam that I've seen before include "Dairy product" , "Spherical cheese" , "milk product" , "Made into popular cheese" , "something to have with crackers" .)