Endless announcement in paper mostly reveals unusual things (7)
I believe the answer is:
exotica
'unusual things' is the definition.
(I've seen this in another clue)
'endless announcement in paper mostly' is the wordplay.
'endless announcement' becomes 'otic' (I can't explain this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'paper' becomes 'exam' (exam paper).
'mostly' means to remove the last letter (most but not all of the word).
'exam' with its final letter taken off is 'exa'.
'otic' inserted within 'exa' is 'EXOTICA'.
'reveals' acts as a link.
Can you help me to learn more?
(Other definitions for exotica that I've seen before include "Glamorous things from abroad" , "Strange, galmorous things from abroad" , "Interesting and strange objects" , "Articles from abroad" , "Unusual articles" .)