Twbydy-am-by-3 Instant

(Roman numeral for 3, "piece" as in a piece of a set).

Alternatively: the answer might be (Roman 3) as the "piece". twbydy-am-by-3

Given typical cryptic answers: I’ll go with (from tri = three, "by 3" = times three, "am" = "I am" = "I" in Latin? No). (Roman numeral for 3, "piece" as in a piece of a set)

But the simplest interpretation: = two-by-two = 4; "am" = AM; "by 3" = next to 3 → "4AM beside 3" → puzzle answer "TRI" (three) as the piece. (Roman numeral for 3