Country hotel's masked ball (7)
I believe the answer is:
lesotho
'country' is the definition.
(Lesotho is an example)
'hotel's masked ball' is the wordplay.
'masked' is an anagram indicator (a disguised or masked form of the letters).
'ball' becomes 'o' (letter resembling a ball).
'hotels' anagrammed gives 'lesoth'.
'lesoth'+'o'='LESOTHO'
(Other definitions for lesotho that I've seen before include "Country, an enclave of South Africa, capital Maseru" , "Kingdom within South Africa" , "Country entirely within South Africa" , "Kingdom that was formerly Basutoland" , "Independent kingdom, an enclave of South Africa" .)