Terrible ingrates, most cross (8)
I believe the answer is:
angriest
'most cross' is the definition.
Both the definition and answer are superlative adjectives. Maybe they are linked in a way I don't understand?
'terrible ingrates' is the wordplay.
'terrible' is an anagram indicator.
'ingrates' anagrammed gives 'ANGRIEST'.
Can you help me to learn more?
(Other definitions for angriest that I've seen before include "Most characteristic of 1950s young men" , "Most annoyed or hostile" , "Most wrathful" , "Most incensed kind of ingrates" , "Most irate and furious" .)