Block some Etonian villains (5)
I believe the answer is:
anvil
'block' is the definition.
(anvil is a kind of block)
'some etonian villains' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'ANVIL' can be found hidden inside 'etonian villains'.
(Other definitions for anvil that I've seen before include "Smithy's last" , "Block on which metal can be hammered" , "Metalworker's block" , "Iron block; incus" , "part of the ear" .)