More sluggish, with yen for sugar (8)
I believe the answer is:
flattery
'more' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'sluggish with yen for sugar' is the wordplay.
I cannot quite see how this works, but
'yen' could be 'y' (resembles the symbol for the currency of Japan) and 'y' is present in the answer.
'sugar' could be 'flatter' (I've seen this before) and 'flatter' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for flattery that I've seen before include "Cosying up" , "flannel" , "Insincere praise (that will get you nowhere?)" , "''Imitation is the sincerest form of . . . . . . . .'' (8)" , "Fawning, false praise" .)