Tango hidden in Pacific nation (5)
I believe the answer is:
tonga
'pacific nation' is the definition.
(country in the Pacific Ocean)
'tango hidden in' is the wordplay.
'hidden in' indicates an anagram.
'tango' anagrammed gives 'TONGA'.
(Other definitions for tonga that I've seen before include "Two-wheeled Indian vehicle" , "Island nation" , "part of Polynesia" , "Pacific Ocean monarchy" , "Polynesian monarchy, member of the Commonwealth" .)