Setter caught on to representation (4)
I believe the answer is:
icon
'to representation' is the definition.
(icon is a kind of representation)
'setter caught on' is the wordplay.
'setter' becomes 'I' (the person that set the crossword).
'caught' becomes 'c' (cricket abbreviation).
'i'+'c'+'on'='ICON'
(Other definitions for icon that I've seen before include "Religious picture on a wooden panel" , "Admired figure" , "found on computer screen" , "Religious image or computer symbol" , "Cultural or computing symbol" .)