What does the cryptic crossword clue "Shape is round, involving a square (8)" mean?

The definition is "square". The wordplay uses an anagram. anagram of IS + ROUND, + A = DINOSAUR; definition: "square" The answer is DINOSAUR.

Shape is round, involving a square (8)

Independent Cryptic #10932 | 7 Down | 2021-10-26 flower