Resort where Benidorm is, less popular (3)
I believe the answer is:
spa
'resort' is the definition.
(spa is a kind of resort)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for spa that I've seen before include "Health resort near a spring" , "Bath - mineral water spring" , "Boston" , "Watering hole" , "town for his health!" .)