Dog longing to be in hot area (5)
I believe the answer is:
hyena
'dog' is the definition.
(thesaurus)
'longing to be in hot area' is the wordplay.
'longing' becomes 'yen' (yen is a kind of longing).
'to be in' indicates putting letters inside.
'hot' becomes 'h'.
'area' becomes 'a' (maths abbreviation).
'h'+'a'='ha'
'yen' placed within 'ha' is 'HYENA'.
(Other definitions for hyena that I've seen before include "Carrion-feeding carnivore" , "Wolf-like animal with cry like laughter" , "Carnivorous mammal" , "Laughing carnivore" , "Dog-like nocturnal mammal of Africa and southern Asia" .)