Green’s Dictionary of Slang

1. imprisonment.

1984

Partridge DSUE (8th edn) 939/2: late C.19–early 20.

2. (Aus.) an informer.

1894		Truth (Sydney) 14 Jan. 6/6: I told them how it was, they had been suspected of being put-aways, and had been followed and the ‘office’ given.
1911		E. Dyson ‘The Truculent Boy’ in Benno and Some of the Push 54: But Mr Goudy did not report the boy. He knew the Beauties were disposed to be resentful to a ‘put-away’.
1953		K. Tennant Joyful Condemned 202: She is a put-away and no help to me.

3. (Aus.) an object or piece of information that gives something away.

1939

K. Tennant Foveaux 180: [He] was heading for Maisie’s flat to establish an alibi when the idea occurred to him that Hamp might have been carrying his, Curly’s gun. What a put-away!