What is the meaning of Knacker?

One who makes knickknacks, toys, etc.

One of two or more pieces of bone or wood held loosely between the fingers, and struck together by moving the hand; a clapper.

A harness maker.

One who slaughters and (especially) renders worn-out livestock (especially horses) and sells their flesh, bones and hides.

One who dismantles old ships, houses, etc. and sells their components.

A member of the Travelling Community; a Gypsy.

A person of lower social class; a chav, skanger or scobe.

A testicle.

An old, worn-out horse.

A collier's horse.

To tire out, exhaust.

To reprimand.

Source: wiktionary.org