What does the cryptic crossword clue "Seasonal mail crams disc with trash somehow (9,5)" mean?

The wordplay uses an anagram. anagram of CRAMS + DISC + TRASH = CHRISTMASCARDS The answer is CHRISTMASCARDS.

Seasonal mail crams disc with trash somehow (9,5)

Daily Mail Cryptic #16668 | 8 Down | 2021-09-21 flower