Expensive-sounding animal (4)
I believe the answer is:
deer
'animal' is the definition.
(deer is a type of animal)
'expensive-sounding' is the wordplay.
'expensive' becomes 'dear' (similar in meaning).
'sounding' shows a homophone (sound like).
'dear' is a homophone of 'DEER'.
(Other definitions for deer that I've seen before include "Wild animal" , "See 23" , "Grazing animal(s)" , "Hoofed grazing animal" , "Perhaps fallow" .)