Occasionally candid journalist describes new adult supplements (7)
I believe the answer is:
addenda
'supplements' is the definition.
('addendum' can be a synonym of 'supplement')
'occasionally candid journalist describes new adult' is the wordplay.
'occasionally' indicates alternate letters.
'journalist' becomes 'ed' (short for editor).
'describes' indicates putting letters inside (describe can mean to form the outline of).
'new' becomes 'n'.
'adult' becomes 'a'.
The alternating letters of 'candid' are 'add'.
'ed' placed around 'n' is 'end'.
'add'+'end'+'a'='ADDENDA'
(Other definitions for addenda that I've seen before include "Textual supplements" , "Extra items put in book" , "Things added to the end of books" , "collection of extra material" , "supplementary pages" .)