One has to get key? (6)
I believe the answer is:
island
'key?' is the definition.
(I've seen this in another clue)
'one has to get' is the wordplay.
'one has to' becomes 'is' (I can't justify this - if you can you should believe this answer much more).
'get' becomes 'land' (landing is a kind of getting).
'is'+'land'='ISLAND'
Can you help me to learn more?
(Other definitions for island that I've seen before include "Refuge as in middle of road" , "Ireland, Jersey or Iceland, say" , "area adjacent to water" , "Rum, for instance" , "Land mass surrounded by water" .)