This writer is taken in by dull unrealistic person? (7)
I believe the answer is:
dreamer
'unrealistic person?' is the definition.
(overly idealistic person)
'this writer is taken in by dull' is the wordplay.
'this writer' becomes 'me' (the person who wrote the clues).
'is taken in by' is an insertion indicator.
'dull' becomes 'drear' (I've seen this before).
'me' going inside 'drear' is 'DREAMER'.
(Other definitions for dreamer that I've seen before include "Gerontius" , "Martin Luther King" , "Mitty type" , "One imagines" , "such an unpractical person!" .)