Larks, in a whirl, land in Indian Ocean (3,5)
I believe the answer is:
sri lanka
'land in indian ocean' is the definition.
(I know that Sri Lanka is a country)
'larks in a whirl' is the wordplay.
'whirl' is an anagram indicator.
'larks'+'in'+'a'='larksina'
'larksina' with letters rearranged gives 'SRI LANKA'.
(Other definitions for sri lanka that I've seen before include "Country in 4" , "It used to be called Ceylon" , "Country off the southeast coast of India" , "land" , "'Formerly Ceylon (3,5)'" .)