Inclined to accept roentgen unit study (8)
I believe the answer is:
learning
'study' is the definition.
(thesaurus)
'inclined to accept roentgen unit' is the wordplay.
'inclined' becomes 'leaning' (similar in meaning).
'to accept' indicates putting letters inside.
'roentgen unit' becomes 'R' (symbol for roentgen, unit of exposure to radiation).
'leaning' enclosing 'r' is 'LEARNING'.
(Other definitions for learning that I've seen before include "(Knowledge from) study" , "Cognitive process of acquiring skill or knowledge" , "Researching - scholarship" , "Erudition - education" , "information" .)