1920s Term for Excellent, Used by Bertie Wooster

This page is the CodyCross answer for the clue below from Past and Present Tech, Group 1454, Puzzle 5 (Dial Up Internet).

Question is: 1920s Term for Excellent, Used by Bertie Wooster

and the answer is: SPIFFING

Word Meaning:

SPIFFING — (British, colloquial, dated) Very good, excellent.

Definitions from Wiktionary.