Inform on a role and see the difference (4,5)
I believe the answer is:
tell apart
'and see the difference' is the definition.
I can't judge whether this definition defines the answer.
'inform on a role' is the wordplay.
'inform' becomes 'tell' (telling is a kind of informing).
'on' means one lot of letters go next to another.
'role' becomes 'part' (eg a part or role in a film).
'tell'+'a'+'part'='TELL APART'
Can you help me to learn more?
(Other definitions for tell apart that I've seen before include "See difference between" , "Rattle pal about - distinguish one from the other" .)