The most common and most likely answer to this crossword clue is the 5 letter word ANVIL
I've seen this crossword clue in Financial Times
A
N
V
I
L
More clues leading to the result ANVIL
- Iron block, a feature of Elizabethan village
- Article: nothing about very small ear bone
- Iron block found in Roman villa
- Number 5 in trouble? Smith beats it
- German villain holds something for forging
- Bone discovered in Roman villa
- Block an uncompleted foul
- Iron block in Roman villa
- It helps forger framed by Machiavellian villain
- Part of Roman villa block
Buddy explains!

The straight part
We know that "Iron block" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case iron block = anvil.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 ANVIL mean?
ANVIL noun- A heavy iron block used in the blacksmithing trade as a surface upon which metal can be struck and shaped.
- An incus bone in the middle ear.
- A stone or other hard surface used by a bird for breaking the shells of snails.
- The non-moving surface of a micrometer against which the item to be measured is placed.
- To fashion on an anvil (often used figuratively).