Actually it's longer than a summer afternoon! (3)
I believe the answer is:
era
'actually it's longer than a' is the definition.
I can't judge whether this defines the answer.
'summer afternoon' is the wordplay.
'ERA' is hidden in amongst the letters.
But, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for era that I've seen before include "Memorable period" , "Long historical period" , "Age marked by a distinctive character" , "Long period of history" , "Age of importance" .)