DIY works in part a source of great value (3,4)

I believe the answer is:

pay dirt

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'a source of great value' is the definition.
I can't tell whether this definition defines the answer.

'diy works in part' is the wordplay.
'works' indicates an anagram (work can mean to twist or convulse).
'in' is an insertion indicator.
'diy' is an anagram of 'ydi'.
'ydi' put within 'part' is 'PAY-DIRT'.

Can you help me to learn more?

(Other definitions for pay dirt that I've seen before include "profitable success" , "Ground containing ore in profitable amounts" , "Rich ore-bearing ground (US)" .)

I've seen this clue in The Times.

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