Adjust mechanism, essentially, saving fortune upgrading it (6)

I believe the answer is:

tuneup

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'adjust mechanism essentially saving' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'fortune upgrading it' is the wordplay.
'TUNEUP' is hidden within the letters.
But, I'm unsure how this is indicated.

Can you help me to learn more?

I've seen this clue in The Irish Times.

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