You and I have nothing but misery (3)
I believe the answer is:
woe
'misery' is the definition.
(woe is a kind of misery)
'you and i have nothing' is the wordplay.
'you and i' becomes 'we'.
'have' is an insertion indicator.
'nothing' becomes 'O' (looks like zero - 0).
'we' enclosing 'o' is 'WOE'.
'but' is the link.
(Other definitions for woe that I've seen before include "Tale content?" , "Difficulty" , "Misery - tribulation" , "Misfortune" , "Grief, misery" .)