What does the cryptic crossword clue "A hairstyle for each month (4)" mean?

The wordplay uses charade, reversal. PER (synonym of "each") + M (abbreviation of "month") [reversal: "hairstyle"] The answer is PERM.

A hairstyle for each month (4)

Guardian Cryptic #29124 | 19 Across | 2023-07-17 flower