Most devout and fiery swallowing untruths (7)
I believe the answer is:
holiest
'most devout' is the definition.
Both the answer and definition are superlative adjectives. Maybe there's a link between them I don't understand?
'fiery swallowing untruths' is the wordplay.
'fiery' becomes 'hot' (synonyms).
'swallowing' means one lot of letters goes inside another.
'untruths' becomes 'lies' (lie is a kind of untruth).
'hot' placed around 'lies' is 'HOLIEST'.
'and' is the link.
Can you help me to learn more?
(Other definitions for holiest that I've seen before include "superlatively untouchable" , "Most pious" , "most befitting to worship" , "Most divine" , "Most resembling sacred work" .)