Some claim agent for representation (5)
I believe the answer is:
image
'representation' is the definition.
(image is a kind of representation)
'some claim agent for' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'IMAGE' can be found hidden inside 'claim agent for'.
(Other definitions for image that I've seen before include "Simile, metaphor" , "Likeness or mental picture" , "Reflection" , "Representation of person or thing" , "Public persona" .)