Settled wild lions in school (9)
I believe the answer is:
colonised
'settled' is the definition.
(I know that settled can be written as colonised)
'wild lions in school' is the wordplay.
'wild' indicates anagramming the letters.
'in' indicates putting letters inside.
'school' becomes 'coed' (a co-educational school).
'lions' with letters rearranged gives 'lonis'.
'lonis' going within 'coed' is 'COLONISED'.
(Other definitions for colonised that I've seen before include "Established settlement" , "settled" , "Occupied'" .)