Moira becomes a New Zealander (5)
I believe the answer is:
maori
'a new zealander' is the definition.
(the Maori are indigenous people of New Zealand)
'moira becomes' is the wordplay.
'becomes' indicates anagramming the letters.
'moira' is an anagram of 'MAORI'.
(Other definitions for maori that I've seen before include "I roam (anag)" , "Native of New Zealand and the Cook Islands" , "Let it stand" , "native people" , "race" .)