Trivial boxer (11)
I believe the answer is:
lightweight
This clue might be a double definition.
'trivial' is the first definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I can't see?
'boxer' is the second definition.
(lightweight is a kind of boxer)
Can you help me to learn more?
(Other definitions for lightweight that I've seen before include "of little importance" , "Fighter" , "Insubstantial" , "delicate" , "Of little substance" .)