Green’s Dictionary of Slang

clinker n.³

a coin.

1857		S.F. Call 26 Mar. n.p.: [He] Went to fight the furious tiger, / Went to fight the beast at faro, / And was cleaned out so completely / That he lost his every mopus, / Every single speck of pewter, / Every solitary shiner, / Every brad and every dollar [...] All the dibs he did discover, / All the browns his uncle lent him, / All the chips and dust and clinkers.
1891		A. Day Mysterious Beggar 216: She kin swing ’round a nour or so, an’ cum in with a big riffle. When she’s home though, she works th’ growler heavy; an’ ’er clinkers don’ last ’er long.