Green’s Dictionary of Slang

walk-up adj.

In phrases

walk-up start (n.)

(Aus.) a certainty.

2003		Age (Melbourne) 7 Aug. 🌐 Warne no walk-up start, says Hookes / Allan Border rates Shane Warne good enough to return straight to the Test team, but the champion leg spinner will not be an automatic selection.
1983		J. Byrell (con. 1959) Up the Cross 101: [of a relationship] The Kraut was on a walk-up start.