Partnersip possibly includes animal (5)
I believe the answer is:
hippo
'animal' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for hippo that I've seen before include "Mammoth African mammal (abbr)" , "Augustine looked after" , "One thick-skinned" , "Beastly sort" , "African river mammal" .)