The most common and most likely answer to this crossword clue is the 8 letter word IRONWARE
I've seen this crossword clue in The Daily Telegraph
I
R
O
N
W
A
R
E
Buddy explains!

The straight part
We know that "Metal pieces" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case metal pieces = ironware.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 IRONWARE mean?
IRONWARE noun- Articles made of iron, as household utensils, tools, and the like.