What does the cryptic crossword clue "A foreboding one is not yet wise? (7)" mean?

The wordplay uses a charade (building blocks). PRE (synonym="PRE") + SAGE (synonym="SAGE") = PRESAGE The answer is PRESAGE.

A foreboding one is not yet wise? (7)

Guardian Cryptic #29519 | 29 Across | 2024-10-21 flower