Lions, primarily, warm and dry in den (4)
I believe the answer is:
lair
'den' is the definition.
(I know that den can be written as lair)
'lions primarily warm and dry' is the wordplay.
'primarily' suggests taking the first letters.
'warm and dry' becomes 'air' (I've seen this before).
The first letter of 'lions' is 'l'.
'l'+'air'='LAIR'
'in' acts as a link.
(Other definitions for lair that I've seen before include "Rail around animal's den" , "Wild animals' habitation" , "animal refuge" , "Wild animal's retreat" , "Flashy man" .)