Egg-laying mammal (7)
I believe the answer is:
echidna
'egg-laying mammal' is the definition.
(echidna is a kind of egg-laying mammal)
This is the entire clue.
(Other definitions for echidna that I've seen before include "Oz native" , "Insectivorous mammal" , "Spiny Aus. mammal" , "One preying on the workers" , "Spiny creature" .)