Animal not usually laden (5)
I believe the answer is:
eland
'animal' is the definition.
(eland is a type of antelope)
'not usually laden' is the wordplay.
'not usually' indicates anagramming the letters (an unusual ordering of the letters).
'laden' with letters rearranged gives 'ELAND'.
(Other definitions for eland that I've seen before include "Large spiral-horned African antelope" , "One browses in the African plain" , "game animal" , "African mammal" , "African beast" .)