Precision of a conservative clergy member on Locke, say (12)

'precision' is the definition.
Both the definition and answer are singular nouns.
Maybe there's an association between them I don't understand?

'a conservative clergy member on locke say' is the wordplay.
I cannot really understand how this works, but
'a' is present in the answer.
'conservative' could be 'c' (UK political abbreviation) and 'c' is found in the answer.
'member' could be 'curate' (I have seen 'Member of clergy ' mean 'curate' so perhaps 'member' could also mean 'curate') and 'curate' is found within the answer.
The remaining letters 'ness' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'of' is the link.

Can you help me to learn more?