Possibly a pie’s a warm brown colour (5)
I believe the answer is:
sepia
'brown colour' is the definition.
(I've seen this before)
'possibly a pie's a' is the wordplay.
'possibly' is an anagram indicator.
'pies' is an anagram of 'sepi'.
'sepi'+'a'='SEPIA'
'warm' acts as a link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sepia that I've seen before include "Brownish tone associated with old photographs" , "Brown tone associated with old photographs" , "Rich reddish-brown colour" , "Reddish-brown; cuttlefish ink" , "tone of pictures?" .)