No longer worried about cover-up by editor (8)
I believe the answer is:
relieved
'no longer worried' is the definition.
(I've seen this in another clue)
'about cover-up by editor' is the wordplay.
'about' becomes 're' (regarding).
'cover-up by' becomes 'liev' (I am not sure about this - if you are sure you should believe this answer much more).
'editor' becomes 'ed' (abbreviation).
're'+'liev'+'ed'='RELIEVED'
Can you help me to learn more?
(Other definitions for relieved that I've seen before include "made easier" , "Removed pain or anxiety" , "Alleviated, eased" , "Freed from distress" , "No longer distressed, reassured" .)