Like some rocks to rock up in Colt (8)

I believe the answer is:

plutonic

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

'like some rocks to' is the definition.
I can't tell whether this defines the answer.

'rock up in colt' is the wordplay.
'rock' indicates anagramming the letters (the solver must 'rock' the letters around).
'up'+'in'+'colt'='upincolt'
'upincolt' is an anagram of 'PLUTONIC'.

Can you help me to learn more?

(Another definition for plutonic that I've seen is " Solidified molten rock".)

I've seen this clue in the Sydney Morning Herald.

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