French articles about catch thrown back by sailor not based on facts (9)
I believe the answer is:
untenable
'not based on facts' is the definition.
(as in an untenable argument)
'french articles about catch thrown back' is the wordplay.
'french articles' becomes 'unable' (I am not sure about this - if you are sure you should believe this answer much more).
'about' means one lot of letters goes inside another.
'catch' becomes 'net' (netting is a kind of catching).
'thrown back' says the letters should be written backwards.
'net' backwards is 'ten'.
'unable' enclosing 'ten' is 'UNTENABLE'.
'by sailor' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
(Other definitions for untenable that I've seen before include "Not defensible" , "unworthy of support?" , "Incapable of being maintained or defended" , "Impossible to defend in argument" , "Incapable of being defended or justified" .)