Deserter left to hang around island is sensible (8)
I believe the answer is:
rational
'is sensible' is the definition.
(associated in meaning)
'deserter left to hang' is the wordplay.
'deserter' becomes 'rat' (both can mean a traitor).
'left' becomes 'l' (common abbreviation).
'to' says to put letters next to each other (I've seen this in other clues).
'hang' becomes 'iona' (I can't explain this - if you can you should believe this answer much more).
'l' after 'iona' is 'ional'.
'rat'+'ional'='RATIONAL'
'around island' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for rational that I've seen before include "In accordance with logic" , "Sane and sensible" , "17 [INTELLIGENT]" , "Conforming to reason" , "Thinking logically" .)