Green’s Dictionary of Slang

a negative intensifier, excessively, extremely; lit. ‘productive of starvation’, e.g. starvation cruel, very cruel.

1892

Kipling ‘Tommy’ in Barrack-Room Ballads (1893) 147: Yes, makin’ mock o’ uniforms that guard you while you sleep / Is cheaper than them uniforms, an’ they’re starvation cheap.