Islamic leader studies religious art (5)
I believe the answer is:
icons
'religious art' is the definition.
'islamic leader studies' is the wordplay.
'leader' indicates taking the first letters.
'studies' becomes 'cons' (conning is a kind of studying).
The first letter of 'islamic' is 'i'.
'i'+'cons'='ICONS'
(Other definitions for icons that I've seen before include "Images, religious perhaps" , "Screen symbols on 4 across" , "Religious pictures" , "Religious or computer images" , "Sacred paintings or computer screen symbols" .)