Awful glutton first to lapse during fast (7)
I believe the answer is:
ghastly
'awful' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ghastly that I've seen before include "Gruesome, repellent" , "Very pale" , "Frightful" , "Dreadful" , "Hideous" .)