Crates should not go here (2-3,4)
I believe the answer is:
no-fly zone
'crates should' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'not go here' is the wordplay.
I cannot really understand how this works, but
'not' could be 'no' (negative) and 'no' is present in the answer.
'go' could be 'fly' (flying is a kind of going) and 'fly' is found within the answer.
The remaining letters 'zone' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for no-fly zone that I've seen before include "'Forbidden airspace (2,3,4)'" , "Area banned to aircraft" , "Airspace in which (military) planes are forbidden" , "Area over which aircraft are forbidden" , "Airspace where no aircraft can go" .)