Set left needing succour (4)
I believe the answer is:
laid
'set' is the definition.
('laid' can be a synonym of 'set')
'left needing succour' is the wordplay.
'left' becomes 'l' (common abbreviation).
'needing' means one lot of letters go next to another.
'succour' becomes 'aid' (I've seen this before).
'l'+'aid'='LAID'
(Other definitions for laid that I've seen before include "Wagered" , "Put down like dial" , "Produced eggs" , "Doze" , "Produced (an egg)" .)