Caesar’s Palace features mineral spring (3)
I believe the answer is:
spa
'mineral spring' is the definition.
(I've seen this in another clue)
'caesar's palace features' is the wordplay.
'features' says the answer is hidden in the clue (I've seen 'featuring' mean this).
'SPA' is hidden within 'caesars palace'.
(Other definitions for spa that I've seen before include "Hydromassage facility" , "Resort with mineral water spring" , "Mineral-water resort" , "Where people go for spring" , "Watering hole" .)