Entertainment, retrospective, from latter epoch (8)
I believe the answer is:
operetta
'entertainment' is the definition.
(I've seen this before)
'retrospective from latter epoch' is the wordplay.
'retrospective' says the letters should be written in reverse.
'from' indicates a hidden word.
'atterepo' is hidden in the letters of 'latter epoch'.
'atterepo' backwards is 'OPERETTA'.
(Other definitions for operetta that I've seen before include "Singing" , "some music theatre" , "The Merry Widow, for example" , "Theatre piece" , "The Student Prince, for example" .)