One studies pictures on screen (5)
I believe the answer is:
icons
'pictures on screen' is the definition.
'icons' can be an answer for 'pictures' (icon is a kind of picture). I'm not certain of the 'on screen' bit.
'one studies' is the wordplay.
'one' becomes 'I' (Roman numeral).
'studies' becomes 'cons' (to con is to study or revise).
'i'+'cons'='ICONS'
Can you help me to learn more?
(Other definitions for icons that I've seen before include "Religious or computer images" , "representative figures?" , "Religious paintings or computer symbols" , "Graphic symbols on computer screens" , "revered art" .)