Parisian venue where French twice will block awkward gremlin (6,5)
I believe the answer is:
moulin rouge
'parisian venue' is the definition.
'where french twice will block awkward gremlin' is the wordplay.
I cannot quite understand how this works, but
'where french' could be 'ou' ('where' in French) and 'ou' is found within the answer.
This explanation may well be incorrect...
(Other definitions for moulin rouge that I've seen before include "Parisian night club, painted by Toulouse-Lautrec" , "cabaret" .)