Green’s Dictionary of Slang

bearded clam n.

[beard n. (1) + SE clam/clam n.1 (2)]

the vagina; one of several terms linking the organ to fish.

Crime Smashers Oct. 30: [comic] Oh, yes! I love your bearded clam! Ooooh...Just be careful...I’m not used to sticks your size!
[US]Trimble 5000 Adult Sex Words and Phrases.
[US]J. Wambaugh Choirboys (1976) 14: He gobbles one beaver and gets promoted. I’ve ate close to three hundred bearded clams in my time and never even got a commendation!
[Aus]B. Humphries Traveller’s Tool 13: They certainly notch up more than their fair share of bearded clams.
[UK](con. WWII) S. Hynes Flights of Passage 44: The female organ was ‘the bearded clam’ or ‘the mossy doughnut’.
[US]S. Morgan Homeboy 74: One eye on the guntoting duck, the other fastened to the Bearded Clam That Ate San Pedro.
[Aus]R.G. Barratt ‘Plenty to Grumble About’ in What Do You Reckon (1997) [ebook] Adoration of Madonna maybe, but not that monster bearded clam.
[UK]Erotic Rev. Mar. 6: There are many, many good uses for tongue and lips where the lilac love lance meets the bearded clam.
[US]CyberAge.com 🌐 Rug Munching 101. A man’s guide to eating bearded clams.
Kurt Rees Fly on the Wall 61: When she found out / the definition of / a bearded clam / everyone laughed again.

In phrases

spear the bearded clam (v.) (also split the bearded clam)

(Aus.) to have sexual intercourse with a woman.

[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 94: If youse get jak of stropping the Mulligan and feel like spearing the bearded clam [...] tell the tart you love her.
[Aus]C. Bowles G’DAY 5: An Australian [...] may be lucky enough to get a good root but he never spears the bearded clam or threads the eye of the golden doughnut.
[UK]J. McDonald Dict. of Obscenity etc.
[US] in Randolph & Legman Ozark Folksongs and Folklore (1992) II 663: Shall we sink the scared sausage? / Shall we split the bearded clam?
[NZ]McGill Reed Dict. of N.Z. Sl.