William-- "Clipped fin" refers to wet-fly/streamer patterns that originated in New England, so called because they are reminiscent of the "lures" old timers made by cutting off the fin of a brook trout and attaching it to a hook. (I'd pretend to be shocked, but I've baited my share of trot-lines with live bream.
) Here's a nice article, with a focus on the patterns Ray Bergman popularized:
http://globalflyfisher.com/patterns/bergman/--look especially at the "Fontanalis Fin" and "Trout Fin."
(BTW, I was referring to the current penultimate pattern with the GP "wing"--Ray can tie faster than I can type.
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