Here’s our phone number — is that corny? (6)
I believe the answer is:
callus
'number is that corny?' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'here's our phone' is the wordplay.
I cannot quite see how this works, but
'phone' could be 'call' (synonyms) and 'call' is present in the answer.
The remaining letters 'us' 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?
(Other definitions for callus that I've seen before include "Thickened skin patch" , "This thick-skinned" , "A sore point" , "Corn" , "Area of hard skin" .)