South African native is overwhelmed by any alarm (5)
I believe the answer is:
nyala
'south african native' is the definition.
(I've seen this before)
'overwhelmed by any alarm' is the wordplay.
'overwhelmed by' indicates a hidden word (the clue has absorbed or overwhelmed the answer).
'NYALA' is hidden within 'any alarm'.
'is' is the link.
(Other definitions for nyala that I've seen before include "Antelope of southern Africa" , "one of a herd" , "South African native" , "wild animal" , "Spiral-horned antelope" .)