What does the cryptic crossword clue "OAP's idle fancy brought in as a digression (8)" mean?

The wordplay uses an anagram. anagram of OAP’S IDLE = EPISODAL The answer is EPISODAL.

OAP's idle fancy brought in as a digression (8)

Independent Cryptic #11725 | 9 Across | 2024-05-09 flower