Green’s Dictionary of Slang

smartly dressed.

1780		R. Tomlinson Sl. Pastoral 3: And I still was as smart as a carrot all day.
1788		Grose Classical Dict. of the Vulgar Tongue (2nd edn) n.p.: Spruce, fine: as smart as a carrot new scraped.
1847		Era (London) 14 Mar. 3: Saw Dilly looking as smart as a fresh scraped carrot.
1890		Gloucester Citizen 8 Nov. 3/5: A brush up once a week makes us as smart as a carrot half scraped.
1894		G.F. Northall Folk-Phrases of Four Counties 11: As smart as a carrot. Said of one gaily dressed.
1922		Beloit Dly Call (KS) 14 Sept. 8/4: ‘You, my dear, [...] would have been smart as a carrot’.
1930		Western Morn. News 9 July 3/4: He’s so smart as a carrot half scraped.
1943		Western Times (Devon) 23 July 2/5: Ees, I reckon [...] Smart’s a carrot half-scraped.
2008		Guardian 20 Nov. 14/1: ‘She’s as smart as a carrot wi’ jugs on’.

(Aus.) very smartly dressed.

1975		personal recollection.
1996		Penguin Bk of More Aus. Jokes 410: He asks him to explain how someone who looks as smart as a rat with a gold tooth can be so silly as to wear a fox hat.

very well dressed.

1937–84

Partridge DSUE (1984) 1094/2: [...] C.20.

very well dressed.

1902

H. Baumann Londinismen (2nd edn).