The spirit of the age (9)
I believe the answer is:
zeitgeist
'the spirit of the age' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for zeitgeist that I've seen before include "Spirit of a generation" , "The spirit of the times, from German" , "General spirit of an age" , "periodic ethos" , "Period spirit" .)