Trendy model ultimately abandoned endangered species (6)
I believe the answer is:
hippos
'ultimately abandoned endangered species' is the definition.
Although both the answer and definition are plural nouns, I can't see how they can define each other.
'trendy model' is the wordplay.
'trendy' becomes 'hip' (I've seen this in another clue).
'model' becomes 'pos' (I am not sure about this - if you are sure you should believe this answer much more).
'hip'+'pos'='HIPPOS'
Can you help me to learn more?
(Other definitions for hippos that I've seen before include "River horses" , "African natives" .)