Old queen achieved nought (4)
I believe the answer is:
dido
'old queen' is the definition.
(legendary queen of Carthage)
'achieved nought' is the wordplay.
'achieved' becomes 'did' (to do something is to achieve it).
'nought' becomes 'O' (O resembles 0).
'did'+'o'='DIDO'
(Other definitions for dido that I've seen before include "Founding queen of Carthage (did next to nothing!)" , "She loved Aeneas" , "Carthaginian heroine" , "Tragic queen" , "Queen < singer" .)