1960s; earliest use found in The Spectator. From pit + a second element of uncertain origin, perhaps a variant (with initial front glide) of hacker, or perhaps from yack, variant of yerk + -er.
Definition of pit yacker in US English:
pit yacker
(also pit yakkor, pit yakker)
nounˈpɪt jakə
English Regional, North depreciative
A coal miner.
Origin
1960s; earliest use found in The Spectator. From pit + a second element of uncertain origin, perhaps a variant (with initial front glide) of hacker, or perhaps from yack, variant of yerk + -er.