Comment about evangelist (6)
I believe the answer is:
remark
'comment' is the definition.
(a remark is a spoken comment)
'about evangelist' is the wordplay.
'about' becomes 're' (regarding).
'evangelist' becomes 'mark' (traditional author of the Gospel of Mark).
're'+'mark'='REMARK'
(Other definitions for remark that I've seen before include "Make mention of" , "Notice or comment on" , "Say as a comment" , "Mention - observe" , "(E.g. Virgil's) pastoral poems" .)