Quality of oil? Blasting of US county will secure it (10)

I believe the answer is:

unctuosity

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'quality of oil? blasting' is the definition.
I can't judge whether this defines the answer.

'of us county will secure it' is the wordplay.
'of' indicates an anagram (the answer comes from or 'of' the letters).
'will secure' is an insertion indicator (inserted letters are secured).
'us'+'county'='uscounty'
'uscounty' with letters rearranged gives 'unctuosy'.
'unctuosy' going around 'it' is 'UNCTUOSITY'.

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