Cut up about greeting piece of early evidence? (7,1)
I believe the answer is:
exhibit a
'piece of early evidence?' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'cut up about greeting' is the wordplay.
I cannot really understand how this works, but
'cut' could be 'bit' (I've seen this in other clues) and 'bit' is located in the answer.
'about' could be 'a' (abbreviation in Chambers) and 'a' is found in the answer.
'greeting' could be 'hi' (hi is a kind of greeting) and 'hi' is found within the answer.
The remaining letters 'ex' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?