It's sweet, son folding a rug (5)
I believe the answer is:
sugar
'it's sweet' is the definition.
(sugar is sweet)
'son folding a rug' is the wordplay.
I cannot quite understand how this works, but
'son' could be 's' (genealogical abbreviation for son) and 's' is present in the answer.
'a' is present in the answer.
an anagram of 'rug' is 'ugr' which is within the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sugar that I've seen before include "flattery" , "Common sweetener" , "Cane or beet sweet stuff" , "See 11" , "Argus (anag.)" .)