Green’s Dictionary of Slang

masher adj.

[masher n. (3)]

flashy, dandified, fashionable.

[UK]Bristol Magpie 2 Jan. 9/1: [I]f the young lady masher would have more respect for herself, and not keep her masher butcher so late on the doorstep, Magpie would not have eyed her.
[Aus]Dead Bird (Sydney) 14 Dec. 7/1: A masher bookmaker and a callco-hawker had four lively rounds in the yard of a city pub. the other day.
[UK]Globe (London) 7 Feb. 1, col. 4: What are umbrellas or masher canes to students immersed in Mill or Emerson [...] ? [F&H].
[Aus]H. Lawson ‘Billy’s “Square Affair”’ in Roderick (1967–9) I 225: He wanted clothes, a masher suit, he wanted boots and hat.
[Aus]Bulletin (Sydney) 13 Oct. 13/1: Bill was in a plight / How to make her foller; / Thought he’d look all right, / In a masher collar.