Very enthusiastic study probing painting, say (6)
I believe the answer is:
ardent
'very enthusiastic' is the definition.
(I've seen this before)
'study probing painting say' is the wordplay.
'study' becomes 'den' (I've seen this before).
'probing' indicates putting letters inside (probe can mean to make a hole in).
'painting say' becomes 'art' (painting is a kind of art).
'den' placed into 'art' is 'ARDENT'.
(Other definitions for ardent that I've seen before include "very interested" , "passion" , "Having great warmth of feeling like a lover" , "Loving and fiery" , "'Fervent, impassioned (6)'" .)