Thought current magazine popular with editor (8)
I believe the answer is:
imagined
'thought' is the definition.
('imagine' can be a synonym of 'think')
'current magazine popular with editor' is the wordplay.
'current' becomes 'I' (symbol for electric current).
'magazine' becomes 'mag' (abbreviation for magazine).
'popular' becomes 'in' ('in' can mean trendy).
'with' says to put letters next to each other.
'editor' becomes 'ed' (abbreviation).
'i'+'mag'+'in'+'ed'='IMAGINED'
(Other definitions for imagined that I've seen before include "Dreamt up" , "Conceived of" , "Formed a mental image" , "Conjured up in the mind" , "Created in the mind" .)