The most common and most likely answer to this crossword clue is the 8 letter word ACCURACY
I've seen this crossword clue in The Sunday Telegraph
A
C
C
U
R
A
C
Y
More clues leading to the result ACCURACY
- Faithfulness — a leading feature of crucial church role
- Precision recognised in a key church office
- Correctness of notes on church office
- Current clerical office’s fidelity
- A Conservative minister’s office showing precision
- A Conservative minister’s office? Watch out if you don’t get this!
- Precision in account supplied by church office
- Faithfulness in a key church position
- In truth Bill has a position as a minister
- Faithfulness of deacon’s core religious position
Buddy explains!

The straight part
We know that "Faithfulness" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case faithfulness = accuracy.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ACCURACY mean?
ACCURACY noun- The state of being accurate; being free from mistakes, this exemption arising from carefulness; exactness; correctness
- Exact conformity to truth, or to a rule or model; degree of conformity of a measure to a true or standard value.