Presumably he was included in Paris art reviews (6)
I believe the answer is:
sartre
'presumably he' is the definition.
The definition suggests a singular noun which matches the answer.
'included in paris art reviews' is the wordplay.
'included in' says the answer is hidden in the clue.
'SARTRE' can be found hidden inside 'paris art reviews'.
'was' is the link.
Can you help me to learn more?
(Other definitions for sartre that I've seen before include "Jean Paul -, French author" , "Jean Paul . . ., French existentialist writer" , "French philosophic writer" , "Sooner" , "Jean-Paul -, French philosopher/author" .)