Verb
To be available or unused.
There's some bacon going spare if anyone wants some more.
(UK, informal) To become very angry; to become frustrated or distraught: see spare.
When he found out that someone had broken the window, he went spare.
The poor girl is going spare, stuck in the house all day with the kids like that.
(archaic) To be unemployed.
Source: en.wiktionary.org