A long time, but less than a generation (3)
I believe the answer is:
era
'a long time' is the definition.
(I've seen this before)
'less than a generation' is the wordplay.
'ERA' is hidden in amongst the letters.
But, I am unsure how the hidden word is indicated.
'but' acts as a link.
Can you help me to learn more?
(Other definitions for era that I've seen before include "Age of importance" , "Long period of history" , "Significant time" , "Memorable period" , "Period, age" .)