Rising resort includes lake and mountains (4)
I believe the answer is:
alps
'mountains' is the definition.
(alp is a kind of mountain)
'rising resort includes lake' is the wordplay.
'rising' says the letters should be written in reverse (going up in a down clue).
'resort' becomes 'spa' (spa is a kind of resort).
'includes' indicates putting letters inside.
'lake' becomes 'l'.
'spa' placed around 'l' is 'spla'.
'spla' back-to-front is 'ALPS'.
'and' acts as a link.
(Other definitions for alps that I've seen before include "Slap about in mountains" , "Mountains in Central Europe" , "South-central European mountain system" , "Mountain system in south-central Europe" , "Mountain pastures" .)