D.E. Big Monday

[Hairyanne]

4 across (3,2,6) Final years of the 19th century, characterised as
a time of decadence and self-doubt.

Many thanks if you can help

[falconfan1]

age of reason?

[Hairyanne]

Thank you falconfan1, I forgot to put in the letters I'd got!
which is F?? D? S?E?L?

[falconfan1]

fin de siecle

[Hairyanne]

Thank you falconfan1

[JandyAF]

The Age of Reason, falconfan1, was actually in the 18th century, the period otherwise known as the Enlightenment.