Heard feline in Siberian forest (5)
I believe the answer is:
taiga
'siberian forest' is the definition.
(I've seen this in another clue)
'heard feline' is the wordplay.
'heard' shows a homophone (sound like).
'feline' becomes 'tiger' (tiger is a kind of feline).
'tiger' is a homophone of 'TAIGA'.
'in' is the link.
(Other definitions for taiga that I've seen before include "Russian zone" , "Arctic coniferous region" , "Marshy pine forest" , "Northern region" , "Swampy forest south of tundra" .)