Author, British, tense visiting French city (6)
I believe the answer is:
blyton
'author' is the definition.
(children's author Enid Blyton)
'british tense visiting french city' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'tense' becomes 't' (abbreviation used in many dictionaries).
'visiting' means one lot of letters goes inside another.
'french city' becomes 'Lyon' (I've seen this before).
't' placed inside 'lyon' is 'lyton'.
'b'+'lyton'='BLYTON'
(Other definitions for blyton that I've seen before include "Enid --, children's author" , "Creator of Noddy" , "See 26 Across" , "Famous Five author, d. 1968" , "Enid --, children's writer" .)