We write about nothing but misery (3)
I believe the answer is:
woe
'misery' is the definition.
(woe is a kind of misery)
'we write about nothing' is the wordplay.
I cannot really understand how this works, but
'nothing' could be 'o' (looks like zero - 0) and 'o' is present in the answer.
'we' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'but' acts as a link.
Can you help me to learn more?
(Other definitions for woe that I've seen before include "Difficulty" , "Alas!" , "Misfortune" , "Misery, great suffering" , "Misery - tribulation" .)