Definition of clam-diggers:
(n) :
A bivalve mollusk of many kinds, especially those that are edible; for example soft-shell clams (Mya arenaria), hard clams (Mercenaria mercenaria), sea clams or hen clams (Spisula solidissima), and other species, possibly originally applied to clams of species Tridacna gigas, a huge East Indian bivalve.
(n) :
(US, slang, chiefly in the plural) A dollar.
(n) :
(slang, vulgar) A vagina or vulva.
(n) :
(informal) One who clams up; a taciturn person, one who refuses to speak.
(n) :
A kind of vise, usually of wood.
(v) :
To dig for clams.