Member of West Indies cult movement, one embraced by South America (2,5)
I believe the answer is:
st lucia
'member of west indies' is the definition.
(St Lucia is part of the West Indies)
'cult movement one embraced by south america' is the wordplay.
'movement' indicates an anagram (letters move around).
'one' becomes 'i' (Roman numeral).
'embraced by' means one lot of letters goes inside another.
'south' becomes 'S' (abbreviation).
'america' becomes 'a' (common abbreviation - e.g. in organisation names).
'cult' with letters rearranged gives 'tluc'.
'tluc'+'i'='tluci'
's'+'a'='sa'
'tluci' placed into 'sa' is 'ST LUCIA'.
(Other definitions for st lucia that I've seen before include "'Volcanic island in the Windward Isles (2,5)'" , "Caribbean country" , "Commonwealth country in the Windward Islands" , "Windward Isles country to the south of Martinique" .)