Due to leave (6)
I believe the answer is:
desert
I believe this clue is a double definition.
'due' is the first definition.
(thesaurus)
'leave' is the second definition.
(desert can mean to leave or abandon)
'to' acts as a link.
(Other definitions for desert that I've seen before include "Merit < leave" , "Abandon in arid area" , "Kalahari, for example" , "Sahara, Gobi, etc" , "Abandon in Sahara" .)