Hawaiian veranda in passage, mostly excellent (5)
I believe the answer is:
lanai
'hawaiian veranda' is the definition.
(I've seen this before)
'in passage mostly excellent' is the wordplay.
'in' means one lot of letters goes inside another.
'passage' becomes 'lani' (I can't justify this - if you can you should believe this answer much more).
'mostly' means to remove the last letter.
'excellent' becomes 'ai'.
'ai' with its last letter taken off is 'a'.
'lani' going around 'a' is 'LANAI'.
Can you help me to learn more?
(Other definitions for lanai that I've seen before include "Hawaiian veranda" , "Place where Hawaiians live" , "Hawaiian living area" .)