Queen of Carthage achieved nothing (4)
I believe the answer is:
dido
'queen of carthage' is the definition.
(I've seen this in another clue)
'achieved nothing' is the wordplay.
'achieved' becomes 'did' (to do something is to achieve it).
'nothing' becomes 'O' (looks like zero - 0).
'did'+'o'='DIDO'
(Other definitions for dido that I've seen before include "She loved Aeneas" , "Carthaginian queen linked to Aeneas" , "The old queen" , "Founding queen of Carthage (did next to nothing!)" , "Tyre lady" .)