A flightless bird once associated with south Pacific state (5)
I believe the answer is:
samoa
'south pacific state' is the definition.
(I've seen this in another clue)
'a flightless bird once associated with' is the wordplay.
'a flightless bird' becomes 'moa' (extinct flightless bird of New Zealand).
'once' becomes 'sa' (I can't justify this - if you can you should believe this answer much more).
'associated with' says to put letters next to each other.
'moa' put after 'sa' is 'SAMOA'.
Can you help me to learn more?
(Other definitions for samoa that I've seen before include "South Pacific island country, gaining its independence from New Zealand in 1962" , "South Pacific island nation" , "Pacific island nation, capital Apia" , "Group of islands in the South Pacific" , "SW Pacific island chain" .)