Suffering of an unmarried philosopher (3)

I believe the answer is:

ill

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'suffering' is the definition.
(suffering with illness)

'an unmarried philosopher' is the wordplay.
'an' becomes 'i' (Roman numeral for one).
'unmarried philosopher' becomes 'll' (I can't justify this - if you can you should believe this answer much more).
'i'+'ll'='ILL'

'of' acts as a link.

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(Other definitions for ill that I've seen before include "Not well, sick" , "Where to find Chicago" , "Seasick" , "Badly - in need of treatment" , "Faulty" .)

I've seen this clue in The Times.

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