What does the cryptic crossword clue "Heavenly sight, delightful to the shepherds (3,3)" mean?

The wordplay uses a charade (building blocks). RED (synonym="RED") + SKY (synonym="SKY") = REDSKY The answer is REDSKY.

Heavenly sight, delightful to the shepherds (3,3)

Guardian Cryptic #26138 | 19 Across | 2013-12-23 flower