Islamic leader studies religious art (5)
I believe the answer is:
Here is my best explanation:
'religious art' is the definition.
'islamic leader studies' is the subsidiary indication.
'leader' suggests taking the first letters.
'studies' becomes 'cons' (conning is a kind of studying).
The first letter of 'islamic' is 'i'.
(Other definitions for icons that I've seen before include "Images, religious perhaps", "Screen symbols on 4 across", "Devotional paintings", "Symbols on computer screens", "Sacred paintings or computer screen symbols", "Religious paintings or computer symbols", "Images or statues, or computer screen symbols", "Religious or computer images", "Computer screen symbols" and "Sonic (anag)".)