Explosive set off covering rock's opening cracks (7)

I believe the answer is:

efforts

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'cracks' is the definition.
The definition and answer can be both acts as well as being plural nouns.
Maybe there's an association between them I don't understand?

'explosive set off covering rock's opening' is the wordplay.
'explosive' indicates anagramming the letters.
'covering' is an insertion indicator.
'opening' says to take the initial letters.
The initial letter of 'rocks' is 'r'.
'set'+'off'='setoff'
'setoff' anagrammed gives 'effots'.
'effots' placed around 'r' is 'EFFORTS'.

Can you help me to learn more?

(Other definitions for efforts that I've seen before include "Determined attempts" , "Exertions" , "Acts of trying hard" , "Endeavours, attempts" .)

I've seen this clue in The Telegraph.

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