The most common and most likely answer to this crossword clue is the 9 letter word SURCHARGE
I've seen this crossword clue in The Daily Telegraph
S
U
R
C
H
A
R
G
E
More clues leading to the result SURCHARGE
- Fish in sudden increase leading to extra demand
- Penalty payment, if cleaner punctures balloon
- Duchess’s last cleaner in drive to get an additional payment
- Extra cost of cleaner during sudden increase in employment
- Cleaner in rush for additional payment
- Heave when swallowing fish supplement
- Rush to pocket daily tax
- It’s swell having tea thrown in for an extra amount
- Caught in rug, share out fleece
- Certain about maid paying final and additional expense
Buddy explains!

The straight part
We know that "extra amount" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case extra amount = surcharge.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 SURCHARGE mean?
SURCHARGE noun- An addition of extra charge on the agreed or stated price.
- An excessive price charged e.g. to an unsuspecting customer.
- An overprint on a stamp that alters (usually raises) the original nominal value of the stamp; used especially in times of hyperinflation.
- A painting in lighter enamel over a darker one that serves as the ground.
- A charge that has been omitted from an account as payment of a credit to the charged party.
- A penalty for failure to exercise common prudence and skill in the performance of a fiduciary's duties.
- An excessive load or burden.
- The putting, by a commoner, of more animals on the common than he is entitled to.
- To apply a surcharge.
- To overload; to overburden.
- To overstock; especially, to put more cattle into (e.g. a common) than one has a right to do, or more than the herbage will sustain.
- To show an omission in (an account) for which credit ought to have been given.