Green’s Dictionary of Slang

clothes-peg n.2

[rhy. sl.; note Franklyn, Dict. of Rhyming Slang (1960) claims this usage is erroneous]

an egg.

1937
1940195019601970198019902000
a.2002
[UK]Partridge DSUE.
[UK]G.D. Smith Cockney Rhy. Sl. 🌐 Clothes Peg: Egg.