Correctness, precision (8)
I believe the answer is:
accuracy
This clue is a double definition.
'correctness' is the first definition.
(accuracy is a kind of correctness)
'precision' is the second definition.
(I've seen this in another clue)
(Other definitions for accuracy that I've seen before include "'Precision, exactness (8)'" , "Absolute correctness" , "faithfulness" , "Correctness - exactitude" , "precise" .)