Make mistake accepting sentimentality: it's worthless (2-4)
I believe the answer is:
no-good
'worthless' is the definition.
(I've seen this in another clue)
'make mistake accepting sentimentality' is the wordplay.
I cannot quite understand how this works, but
'sentimentality' could be 'goo' (informal term for sentimentality) and 'goo' is found within the answer.
'mistake' could be 'nod' (I have seen 'Careless mistake' mean 'nod' so perhaps 'mistake' could also mean 'nod') and 'nod' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'it's' is the link.
Can you help me to learn more?
(Another definition for no-good that I've seen is " (Of a person) beneath contempt".)