Topic (5)
'topic' is the definition.
(I know that topic can be written as theme)
This is all the clue.
(Other definitions for theme that I've seen before include "Melody on which variations are constructed" , "Main idea or topic" , "Subject (on which person writes, speaks)" , "Unifying motif" , "matter for discussion" .)
'topic' is the definition.
(I know that topic can be written as subject)
This is the entire clue.
(Other definitions for subject that I've seen before include "Theme (of a fugue)" , "Person under 26?" , "issue" , "Branch of knowledge" , "One is under the authority of royalty" .)