Twbydy-am-by-3

However, if the dash before "piece" means the answer is hyphenated, "three-piece" fits, but the clue gives 3 letters. Could it be ?

Alternatively: the answer might be (Roman 3) as the "piece".

But simpler: the answer is likely (three in prefix form) — but "twbydy"?? Maybe "tw" = two, "bydy"??

But without more context, the cleanest match to a 3-letter "piece" is (as in a piece of something) — but the wordplay "twbydy" doesn't yield that.