Green’s Dictionary of Slang

(US Und.) a bail bondsman.

1949		Monteleone Criminal Sl. (rev. edn).
1950		Goldin et al. DAUL 204/2: Springer. Bail bondsman; lawyer; any political or other fixer.
1986–7		Maledicta IX 150: The original argot of prostitution includes some words and phrases which have gained wider currency and some which have not […] springer (bail bondsman).