Great performance from Venetian queen once (7)
I believe the answer is:
blinder
'great performance' is the definition.
'blinder' can be an answer for 'performance' (I have seen 'Outstanding performance' mean 'blinder' so perhaps 'performance' could also mean 'blinder'). I'm not sure about the 'great' bit.
'from venetian queen once' is the wordplay.
I cannot really understand how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is present in the answer.
'queen' could be 'er' (short for Elizabeth Regina ie Queen Elizabeth) and 'er' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for blinder that I've seen before include "Marvellous performance" , "as Cornwall, as against Gloucester" , "the boy in "Equus"?" , "Spectacular sporting performance" , "drunken orgy" .)