Animal that's long occupying heart of Sahara (5)
I believe the answer is:
hyena
'animal' is the definition.
(thesaurus)
'long occupying heart of sahara' is the wordplay.
'long' becomes 'yen' ('yen' can be a synonym of 'long').
'occupying' is an insertion indicator.
'heart of' indicates the central letters.
The centre of 'sahara' is 'ha'.
'yen' inserted inside 'ha' is 'HYENA'.
'that's' is the link.
(Other definitions for hyena that I've seen before include "Dog-like animal with howl like laughter" , "Dog-like scavenger" , "Scavenging carnivore" , "Creature" , "Dog-like carrion eater" .)