Country singer Clay Walker is in hot water after getting caught on audio berating his bus driver ... but Clay tells us it went down a year ago, and it's all water under the bridge.
Clay starts by saying he could easily whup the driver's ass. The singer also claims the driver didn't show on time ... and Clay is PISSED.
It's pretty harsh ... and just when it sounds like all is said and done, Clay finds another reason to call him out.
While this is clearly an intense one-sided convo, Clay tells TMZ ... "This happened over a year ago, and it came at the end of a long, tough weekend. The bus driver and I reconciled immediately, and we are friends and stay in touch.”
FYI -- Clay's been in the country game since his debut record in the early '90s ... first topping the charts with his single, "What's It to You."
He was spending the day with the Texas House of Reps. Wednesday -- thanking people for their support of his nonprofit org, Band Against MS ... committed to helping people with multiple sclerosis ... something he's battled since 1996.