Specially, but in only one way (8)

I believe the answer is:

uniquely

I'm a little stuck... Click here to teach me more about this clue!

'specially but in' is the definition.
Both the answer and definition are adverbs. Perhaps there's an association between them I don't understand?

'only one way' is the wordplay.
'only' becomes 'unique' (synonyms).
'one way' becomes 'ly' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'unique'+'ly'='UNIQUELY'

Can you help me to learn more?

(Another definition for uniquely that I've seen is " In unprecedented fashion".)

I've seen this clue in the Evening Standard.

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