Stuff that’s sweet and endlessly virtuous? (3)
I believe the answer is:
goo
'stuff that's sweet' is the definition.
(goo can refer to sentimentality)
'endlessly virtuous?' is the wordplay.
'endlessly' means to remove the last letter.
'virtuous?' becomes 'good' (associated in meaning).
'good' with its final letter taken away is 'GOO'.
'and' acts as a link.
(Other definitions for goo that I've seen before include "Anything sticky" , "syrup" , "Sticky matter" , "Substance that's viscous" , "Sticky substance (colloq.)" .)