I have visions, mostly dull, about myself (7)
I believe the answer is:
dreamer
'i have visions mostly' is the definition.
I can't judge whether this definition defines the answer.
'dull about myself' is the wordplay.
'dull' becomes 'drear' (I've seen this before).
'about' means one lot of letters goes inside another.
'myself' becomes 'me'.
'drear' placed around 'me' is 'DREAMER'.
Can you help me to learn more?
(Other definitions for dreamer that I've seen before include "stargazer" , "Gerontius" , "One lost in abstraction" , "One who tends to live in an unreal world" , "Idealist - visionary" .)