Health facility in Cairngorms park (3)
I believe the answer is:
spa
'health facility' is the definition.
(I've seen this in another clue)
'in cairngorms park' is the wordplay.
'in' says the answer is hidden in the clue.
'SPA' can be found hidden inside 'cairngorms park'.
(Other definitions for spa that I've seen before include "Watering hole" , "Cheltenham or Bath?" , "town in Belgium" , "Watering-place" , "place of treatment" .)