Landed outside Channel Islands according to legal requirements (5)
I believe the answer is:
licit
'according to legal requirements' is the definition.
'landed outside channel islands' is the wordplay.
'landed' becomes 'lit' (I've seen this in other clues).
'outside' is an insertion indicator.
'channel islands' becomes 'ci'.
'lit' enclosing 'ci' is 'LICIT'.
(Other definitions for licit that I've seen before include "Legal" , "Legitimate" , "not banned" , "OK?" , "Sanctioned" .)