Green’s Dictionary of Slang

dimber-damber adj.

[adjectival use of the lit. meaning of dimber-damber n.; note Partridge claims Hotten’s definition is ‘open to grave suspicions’]

smart, neat.

[UK]Hotten Dict. of Modern Sl. etc. 31: DIMBER DAMBER, very pretty.
[Aus]Melbourne Punch ‘City Police Court’ 3 Oct. 234/1: The Mayor.– Prisoner at the bar, you are a dimber damber kiddy, but you are done for a ramp.
[UK]Hotten Sl. Dict.
[US]Minneapolis Jrnl (MN) 24 Jan. 19/3: Yes, gents, I’m a dimber-damber upright man.
[UK] press cutting in J. Ware Passing Eng. of the Victorian Era 109/1: He is a bit dimber-damber, and up to everything on the carpet.