save one’s groats, v. — Green’s Dictionary of Slang

save one’s groats v.

[university custom, those taking their finals deposit nine groats (= 36 old pennies) with an academic officer; if they pass with honours the groats are returned]

to succeed, to do well.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Groats, to save his groats, to come off handsomely. At the universities, nine groats are deposited in the hands of an academic officer, by every person standing for a degree, which if the depositor obtains with honor, are returned to him.
1803		‘A Pembrochian’ Gradus ad Cantabrigiam 69: To save his groats, to come off handsomely.
1811		Lex. Balatronicum [as cit. 1785].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.