Animal desire? Husband essentially mad about it! (5)
I believe the answer is:
hyena
'animal' is the definition.
(thesaurus)
'desire? husband essentially mad about it' is the wordplay.
'desire?' becomes 'yen' (yen is a kind of desire**).
'husband' becomes 'h'.
'essentially' says to take the centre.
'about it' indicates putting letters inside.
The central letter of 'mad' is 'a'.
'h'+'a'='ha'
'yen' put into 'ha' is 'HYENA'.
(Other definitions for hyena that I've seen before include "Spotted scavenger" , "Scavenging carnivore" , "Carrion-eating mammal" , "Afr. doglike carnivore" , "Meat-eater" .)