crack·ing 
/ˈkrækɪŋ/ adjective
always used before a noun /ˈkrækɪŋ/ adjective Brit, informal : very good or impressive
▪ I think it's a cracking story. ▪ The horses set off at a cracking [=very fast] pace around the track.
▪ I think it's a cracking story. ▪ The horses set off at a cracking [=very fast] pace around the track.
— cracking adverb always used before a noun Brit, informal
▪ I think it's a cracking good story.
▪ I think it's a cracking good story.
