Really stuck on the following:
10a Whupping good, replacing starter, moving fast g-/l-o---g
15d Not popular with crackers, Devon Blue o---l-v-d (suspect it's an anagram of devon blue -but what?)
The answer is clearly CLUE as it is a hint and rhymes with a corresponding answer, BLUE as is common in the Everyman nowadays. But how does “describing a piece of language?” give CLUE.