Feline, of course, heard (4)
I believe the answer is:
lynx
'feline' is the definition.
(lynx is a kind of feline)
'course heard' is the wordplay.
'course' becomes 'links' (links is a kind of course).
'heard' indicates a 'sounds like' (homophone) clue.
'links' is a homophone of 'LYNX'.
'of' acts as a link.
(Other definitions for lynx that I've seen before include "European wild cat" , "One of the wild cats" , "Sharp-eyed cat" , "Wild cat -- text browser" , "Member of the cat family" .)