One half of sermon getting into goodness and suffering (6)
I believe the answer is:
misery
'suffering' is the definition.
(I have seen 'Great suffering' mean 'misery' so perhaps 'suffering' could also mean 'misery')
'one half of sermon getting into goodness' is the wordplay.
'one' becomes 'i' (Roman numeral).
'half of' indicates taking half.
'getting into' indicates putting letters inside.
'goodness' becomes 'my' (both are exclamations of surprise).
'sermon' halved is 'ser'.
'i'+'ser'='iser'
'iser' going within 'my' is 'MISERY'.
'and' acts as a link.
(Other definitions for misery that I've seen before include "Despair" , "Feeling of great unhappiness" , "Party-pooper" , "Wretched conditions" , "Intense unhappiness" .)