Find out layer to get warmer (8)
I believe the answer is:
heartier
'warmer' is the definition.
('hearty' can be similar in meaning to 'warm')
'find out layer' is the wordplay.
'find out' becomes 'hear' ('hear' can be a synonym of 'find out').
'layer' becomes 'tier' (tier is a kind of layer).
'hear'+'tier'='HEARTIER'
'to get' is the link.
(Other definitions for heartier that I've seen before include "More red-blooded - rehear it (anag)" , "becoming less restrained" , "more energetic" , "more robust" , "becoming less inhibited?" .)