It's in Belgium, and takes in Spain (3)
I believe the answer is:
spa
'spain' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for spa that I've seen before include "Bath - mineral water spring" , "A curative mineral spring, or place with one" , "A therapeutic hot spring" , "Resort with mineral water spring" , "town in Belgium" .)