Autocat, say, not coming up to scratch in the Blitz? (6-7)

'blitz?' is the definition.
(thesaurus)

'autocat say not coming up to scratch in the' is the wordplay.
I cannot really see how this works, but
'not' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
'in' is found in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?