What does the cryptic crossword clue "Cheek turned by stern religious adherent (7)" mean?

The wordplay uses a reversal. LIP (reversal="LIP") + GRIM (synonym="GRIM") = PILGRIM The answer is PILGRIM.

Cheek turned by stern religious adherent (7)

Independent Cryptic #11614 | 24 Across | 2024-01-01 flower