Green’s Dictionary of Slang

1. (US Und.) a confidence trickster’s victim, a sucker [? the image of the gossipy writer as ‘swallowing’ any story].

1940		D. Maurer Big Con 132: I felt sorry for him, because he was such an understanding winchell.
1940		C. Rawson Headless Lady (1987) 46: Dip is a winchell [...] A sucker word. It’s so well-known to the layman that only the old-timers among the professionals still use it.
1983		Neaman & Silver Euphemisms 184: Victims are variously [...] eggs, savages and winchells.

2. a generic term for a gossip columnist.

1940

J.H. O’Hara Pal Joey 6: This local Winchell took a personal dislike to me and made a couple of cracks about us.