Marsupial black at the tail, with nothing in the way of stomach (5,4)
I believe the answer is:
koala bear
'marsupial' is the definition.
(koala bear is a kind of marsupial)
'black at the tail with nothing in the way of stomach' is the wordplay.
'at the tail' indicates one should take the final letters (the last letter is the tail of the word).
'with nothing' becomes 'o' (I've seen this in other clues).
'in the way of' becomes 'ala' ('a la', French phrase meaning 'in the style of').
'stomach' becomes 'bear' (both can mean to tolerate or endure).
The final letter of 'black' is 'k'.
'k'+'o'+'ala'+'bear'='KOALA BEAR'
(Other definitions for koala bear that I've seen before include "Native of Australia" , "Eucalyptus eater" , "Australian animal" , "Aussie tree-hugger" , "Australian arboreal marsupial" .)