Thought anyone but myself available (6)
I believe the answer is:
notion
'thought' is the definition.
(notion is a kind of thought)
'anyone but myself available' is the wordplay.
I cannot quite see how this works, but
'myself' could be 'i' and 'i' is found within the answer.
'available' could be 'on' (I've seen this in other clues) and 'on' is found in the answer.
The remaining letters 'not' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for notion that I've seen before include "Vague impression" , "Vague idea or opinion" , "Caprice" , "A vague and possibly incorrect opinion" , "Idea, concept" .)