Thoughtful writers originally illustrating victory in Europe (7)
I believe the answer is:
pensive
'thoughtful' is the definition.
(similar in meaning)
'writers originally illustrating victory in europe' is the wordplay.
'writers' becomes 'pens' (writing implements).
'originally' suggests taking the first letters.
'victory in europe' becomes 'VE' (abbreviation as in 'VE Day').
The initial letter of 'illustrating' is 'i'.
'pens'+'i'+'ve'='PENSIVE'
(Other definitions for pensive that I've seen before include "Preoccupied" , "in a brown study?" , "Thinking deeply" , "Brooding" , "Introspective, maybe moody" .)