Nice day, on reflection, for correspondent (6)
I believe the answer is:
journo
'nice day' is the definition.
The definition suggests a singular noun which matches the answer.
'on reflection for correspondent' is the wordplay.
'reflection' shows that the letters should be reversed in order.
'for' says to put letters next to each other (I've seen this in other clues).
'correspondent' becomes 'jour' (I can't justify this - if you can you should believe this answer much more).
'on' back-to-front is 'no'.
'no' after 'jour' is 'JOURNO'.
Can you help me to learn more?
(Other definitions for journo that I've seen before include "Newspaper employee (slang)" , "Hack" , "sub?" , "Newspaper writer, colloquially" .)