Green’s Dictionary of Slang

leven yenneps n.

elevenpence.

1859		Hotten Dict. of Modern Sl. etc. 128: NEVELE YENEPS, elevenpence, – generally leven yeneps.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 23/1: Leven ... Elevenpence.
1873		Sl. Dict.
1935		R.T. Hopkins Life and Death at the Old Bailey 65: Costermongers invariably use the following terms in discussing money transactions [...] Leven – Eleven pence.