Sweet idol relishes every so often retired boxer's protection (9)

'boxer's protection' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?

'sweet idol relishes every so often retired' is the wordplay.
'sweet' becomes 'gum' (gum is a kind of sweet).
'every so often' means one should take alternating letters.
'retired' says the letters should be written backwards.
'idol'+'relishes'='idolrelishes'
The alternating letters of 'idolrelishes' are 'dleihs'.
'dleihs' in reverse letter order is 'shield'.
'gum'+'shield'='GUMSHIELD'

Can you help me to learn more?