Thank you so much, Scorpiojo and Tevor.
With all the help you have given, I now might be able to give more letters to the answers! Although as I said at the beginning, many clues contain numbers / figures, and it's not clear whether they refer to other clues.
Snake's eaten 'enrietta! _ D _ E _ ( Adder? Why?)
Language not used by this Frenchman (6)
_ A _ _ _ _