Mocks Mr. O'Connor who has dire trouble (7)

I believe the answer is:

derides

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'mocks mr o'connor who has dire trouble' is the definition.
'derides' can be an answer for 'mocks' (I've seen this in another clue). I'm unsure of the rest of the definition.

'who has dire trouble' is the wordplay.
'who' becomes 'des' (I can't justify this - if you can you should believe this answer much more).
'has' indicates putting letters inside.
'trouble' indicates an anagram.
'dire' with letters rearranged gives 'ride'.
'des' enclosing 'ride' is 'DERIDES'.

Can you help me to learn more?

(Other definitions for derides that I've seen before include "Laughs at" , "Mocks, scorns" , "Ridicules" .)

I've seen this clue in The Irish Independent.

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