Sozzled, nevertheless seeming pretty bright (3,2)
I believe the answer is:
lit up
'sozzled' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives can sometimes mean the same thing.
'nevertheless seeming pretty bright' is the wordplay.
I cannot really see how this works, but
'bright' could be 'lit' (similar in meaning) and 'lit' is located in the answer.
The remaining letters 'up' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lit up that I've seen before include "high" , "Prepared to smoke" , "bulb so transformed room?" , "was illuminating" , "Drunk (as a bulb?)" .)