Descends on eccentric who provides presentation (5,4)

'presentation' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'descends on eccentric who' is the wordplay.
'descends' becomes 'slides' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' means one lot of letters goes inside another.
'eccentric' indicates anagramming the letters.
'who' anagrammed gives 'how'.
'slides' inserted into 'how' is 'SLIDE SHOW'.

'provides' is the link.

Can you help me to learn more?