Animal showing compassion, by the sound of it (4)
I believe the answer is:
hart
'animal' is the definition.
(I've seen this before)
'compassion by the sound of it' is the wordplay.
'compassion' becomes 'heart' (I've seen this in another clue).
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'heart' sounds like 'HART'.
'showing' is the link.
(Other definitions for hart that I've seen before include "Male deer; Rodgers collaborator" , "Mature male deer" , "Songwriting partnership, Rodgers and --" , "providing material for Richard Rodgers?" , "Male red-deer" .)