Green’s Dictionary of Slang

gear adj.1

also geer
[gear n. (1); at peak popularity one of the Beatles’ supposed favourite words; post-1960s use is ironic]

excellent, wonderful, just right; often as the gear.

[UK]Mersey Beat 20 Sept.–4 Oct. n.p.: The first time it was pretty rough, but we all had a geer time.
[US]‘Hy Lit’ Hy Lit’s Unbelievable Dict. of Hip Words 17: (it’s) gear – British expression for anything great, excellent, tough, boss, out-of-sight.
[UK]S. Berkoff Decadence in Decadence and Other Plays (1985) 19: How splendid spiffing whizzo fab and gear.
P. Smith Two of Us 140: There was a Beatles-themed cruise to the Sea of Cortex in Mexico, even a Liverpool-based ‘fab, gear, groovy, cool, out-of-sight corporate teambuilding workshop.’.