Enthusiastic study in pictures (6)
I believe the answer is:
ardent
'enthusiastic' is the definition.
(similar in meaning)
'study in pictures' is the wordplay.
'study' becomes 'den' (term for a study or office).
'in' is an insertion indicator.
'pictures' becomes 'art'.
'den' placed within 'art' is 'ARDENT'.
(Other definitions for ardent that I've seen before include "'Fervent, impassioned (6)'" , "Fervid" , "passion" , "Passionate, full of feeling" , "Zealous - ranted (anag)" .)