The most common and most likely answer to this crossword clue is the 7 letter word SAVINGS
I've seen this crossword clue in The Daily Telegraph
S
A
V
I
N
G
S
Buddy explains!

The straight part
We know that "amount in the bank?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case amount in the bank? = savings.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 SAVINGS mean?
SAVINGS noun- A reduction in cost or expenditure.
- (usually in the plural) Something (usually money) that is saved, particularly money that has been set aside for the future.
- The action of the verb to save.
- Exception; reservation