Boxing heavyweight, raised outside Lima, eaten by bear (5,3)

'boxing' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see a link between them that I can't see?

'heavyweight raised outside lima eaten by bear' is the wordplay.
'heavyweight' becomes 'ton' (a ton weighs a lot).
'raised' shows that the letters should be reversed in order (going up in a down clue).
'outside' is an insertion indicator.
'lima' becomes 'L' (phonetic alphabet: alpha, bravo, charlie etc.).
'eaten by' means one lot of letters goes inside another (inserted letters get eaten).
'ton' back-to-front is 'not'.
'l' put within 'bear' is 'blear'.
'not' placed around 'blear' is 'NOBLE ART'.

Can you help me to learn more?