Amusingly trivial work is awful to repeat (8)
I believe the answer is:
operetta
'amusingly trivial work' is the definition.
'operetta' can be an answer for 'work' (operetta is a type of musical work). I am unsure of the 'amusingly trivial' bit.
'awful to repeat' is the wordplay.
'awful' indicates anagramming the letters.
'to'+'repeat'='torepeat'
'torepeat' anagrammed gives 'OPERETTA'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for operetta that I've seen before include "Light classical musical comedy-drama" , "G&S production, perhaps" , "Make short work" , "La belle Helene, say" , "The Mikado or Pirates of Penzance, say" .)