Somewhat round bell on Kailasa hill (5)
I believe the answer is:
knoll
'hill' is the definition.
(knoll is a kind of hill)
'somewhat round bell on kailasa' is the wordplay.
'round' is a reversal indicator.
'somewhat' indicates a hidden word.
'llonk' is hidden in the letters of 'bell on kailasa'.
'llonk' in reverse letter order is 'KNOLL'.
(Other definitions for knoll that I've seen before include "Small rounded hill" , "Little hill" , "Small hill or mound" , "Hummock" , "Small round hill" .)