Mammal’s four limbs it oddly passed over (5)
I believe the answer is:
oribi
'mammal's' is the definition.
(oribi is a type of mammal)
'four limbs it oddly passed over' is the wordplay.
'oddly passed over' indicates alternate letters (letters in odd-numbered positions removed).
'four'+'limbs'+'it'='fourlimbsit'
The alternating letters of 'fourlimbsit' are 'ORIBI'.
(Other definitions for oribi that I've seen before include "small hoofed beast" , "Savannah antelope" , "Beastly sort" , "resident of Savannah" , "Creature" .)