What does the cryptic crossword clue "Mould precast in various ranges (7)" mean?

The definition is "ranges". The wordplay uses an anagram. anagram of PRECAST = SPECTRA; definition: "various ranges" The answer is Spectra.

Mould precast in various ranges (7)

Telegraph Prize Cryptic #3028 | 17 Across | 2019-11-03 flower