The most common and most likely answer to this crossword clue is the 7 letter word ACCOUNT
I've seen this crossword clue in The Daily Telegraph
A
C
C
O
U
N
T
More clues leading to the result ACCOUNT
- Story a nobleman read aloud
- A Conservative peer featuring in story
- Bill’s relation
- Description of a nobleman taking in clubs
- Dracula, perhaps, put on a cape, one in red or black?
- . Italian peer supporting a conservative bill
- Bill’s story
- Report a n-nobleman
- Judge an aristocrat by his voice
- Story of Dracula, say
Buddy explains!

The straight part
We know that "Tab" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tab = account.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 ACCOUNT mean?
ACCOUNT noun- A registry of pecuniary transactions; a written or printed statement of business dealings or debts and credits, and also of other things subjected to a reckoning or review.
- A sum of money deposited at a bank and subject to withdrawal.
- A statement in general of reasons, causes, grounds, etc., explanatory of some event; a reason of an action to be done.
- A reason, grounds, consideration, motive; a person's sake.
- A business relationship involving the exchange of money and credit.
- A record of events; recital of transactions; a relation or narrative; a report; a description.
- An estimate or estimation; valuation; judgment.
- Importance; worth; value; esteem; judgement.
- An authorization to use a service.
- A reckoning; computation; calculation; enumeration; a record of some reckoning.
- Profit; advantage.
- To provide explanation.
- To count.