Unusual desire to live (6)
I believe the answer is:
reside
'live' is the definition.
(residing is a kind of living)
'unusual desire' is the wordplay.
'unusual' is an anagram indicator.
'desire' is an anagram of 'RESIDE'.
'to' acts as a link.
(Other definitions for reside that I've seen before include "Make one's home permanently" , "'Live, dwell (6)'" , "Lodge" , "Live in permanently" , "Live (at an address)" .)