Disheartened union is convinced they're dithering (6)
I believe the answer is:
unsure
'dithering' is the definition.
The definition and answer are not the same part of speech.
'disheartened union is convinced' is the wordplay.
'disheartened' says to hollow out the word (remove centre letters) (the middle or heart is removed).
'is convinced' becomes 'sure' (similar in meaning).
'union' with its centre taken out is 'un'.
'un'+'sure'='UNSURE'
'they're' is the link.
Can you help me to learn more?
(Other definitions for unsure that I've seen before include "Not certain or confident" , "Not certain, doubtful" , "Far from certain" , "Not certain, undecided" , "Hesitant" .)