This article is from the Crosswords FAQ, by James A. Lundon (jlundon@xstacy.enet.dec.com) with numerous contributions by others.
Thanks to Ilana Stern for this description.
Indirect anagrams are clues where the actual word to be anagrammed
doesn't appear in the clue; rather a synonym or pointer does. This
type of clue is frowned upon by most (not all; but those who don't
like it generally consider it completely unfair) because it's quite
hard.
Example: Train part of a swirling snowflake, for example (7)
Solution: FLATCAR = train part, swirling = anag. indicator,
snowflake, for example = fractal (which anagrams to flatcar).
This is an incredibly bad and difficult clue! The general rule is
that any letters to be anagrammed must be actually present in the clue.
 
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