Excavator runs in pursuit of one claim in rocky situation (9)

I believe the answer is:

coalminer

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'excavator runs in pursuit' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'of one claim in rocky situation' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or \'of\' the letters).
'in rocky situation' becomes 'r' (I can't explain this - if you can you should believe this answer much more).
'one'+'claim'='oneclaim'
'oneclaim' is an anagram of 'coalmine'.
'coalmine'+'r'='COALMINER'

Can you help me to learn more?

(Other definitions for coalminer that I've seen before include "Worker given pick" , "man down for work?" .)

I've seen this clue in The Telegraph.

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