Area is overrun by flipping tiny creatures! (6)
I believe the answer is:
llamas
'creatures' is the definition.
(llama is an animal of South America)
'area is overrun by flipping tiny' is the wordplay.
'area' becomes 'a' (maths abbreviation).
'is overrun by' indicates putting letters inside (I've seen this in other clues).
'flipping' says the letters should be written in reverse.
'tiny' becomes 'small' (similar in meaning).
'small' backwards is 'llams'.
'a' inserted inside 'llams' is 'LLAMAS'.
(Other definitions for llamas that I've seen before include "Andean pack animals" , "South American animals like the camel" , "Camel-like animals" , "S American animals related to the camel" , "domesticated guanacos" .)