Criminal slain in North Arabian desert — we are all in it together (2,3,2,2,6)
I believe the answer is:
no man is an island
'we are all in it together' is the definition.
('no man is an island' is a John Donne quote)
'criminal slain in north arabian desert' is the wordplay.
I cannot really understand how this works, but
an anagram of 'slain' is 'anisl' which is present in the answer.
'north' could be 'n' (abbreviation) and 'n' is present in the answer.
'arabian' could be 'omani' (someone from Oman) and 'omani' is found within the answer.
'desert' could be 'sand' (I've seen this before) and 'sand' is located in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for no man is an island that I've seen before include "answering question: are Douglas et al on mainland?" , "What poet had to say" , "Line from Meditation XVII (Donne) (2,3,2,2,6)" , "Everyone needs help" , "We depend on each other" .)