Went off thoroughly confused (6)
I believe the answer is:
addled
'thoroughly confused' is the definition.
(I've seen this in another clue)
'went off' is the wordplay.
I cannot really understand how this works, but
'went' could be 'led' (leading is a kind of going) and 'led' is found within the answer.
The remaining letters 'add' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for addled that I've seen before include "Of egg, rotten and producing no chick" , "Corrupt" , "(Of an egg) went bad" , "Confused (wits); made rotten" , "Confused and vague" .)