The most common and most likely answer to this crossword clue is the 4 letter word MASS
I've seen this crossword clue in Independent
M
A
S
S
More clues leading to the result MASS
- Abbreviated state service
- Mother's meeting son for church service
- Press article hidden among manuscripts
- Lots of people in a state, briefly
- Church service prompt cued badly, caused by large-scale Creation?
- Considerable number in religious service
- Size and state of Boston
- Collect for service
- What’s meant by the end of Salem’s Lot?
- Male donkey’s load
Buddy explains!

The straight part
We know that "Large amount" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case large amount = mass.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 MASS mean?
MASS noun- (physical) Matter, material.
- A large quantity; a sum.
- To form or collect into a mass; to form into a collective body; to bring together into masses; to assemble.
- To have a certain mass.
- Involving a mass of things; concerning a large quantity or number.
- Involving a mass of people; of, for, or by the masses.
- The Eucharist, now especially in Roman Catholicism.
- Celebration of the Eucharist.
- (usually as the Mass) The sacrament of the Eucharist.
- A musical setting of parts of the mass.
- To celebrate mass.