Covers boxing learner's knockout performances (8)

'performances' is the definition.
Although both the answer and definition are plural nouns, I can't see how they can define each other.

'covers boxing learner's knockout' is the wordplay.
'covers' becomes 'blinds' (blind is a kind of cover).
'boxing' is an insertion indicator ('box' can mean contain, as in to put in a box).
'learner's knockout' becomes 'er' (I can't justify this - if you can you should give a lot more credence to this answer).
'blinds' placed around 'er' is 'BLINDERS'.

Can you help me to learn more?