Disease in which mercy a goal potentially (10)

I believe the answer is:

acromegaly

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'disease' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'mercy a goal potentially' is the wordplay.
'potentially' indicates anagramming the letters (letters have the potential to spell a new word).
'mercy'+'a'+'goal'='mercyagoal'
'mercyagoal' is an anagram of 'ACROMEGALY'.

'in which' is the link.

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I've seen this clue in The Independent.

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