One serves meat that’s more tough (7)
I believe the answer is:
butcher
'one serves meat' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'more tough' is the wordplay.
I cannot really see how this works, but
'tough' could be 'butch' (I've seen this before) and 'butch' is located in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'that's' is the link.
Can you help me to learn more?
(Other definitions for butcher that I've seen before include "more manly" , "To hack into pieces" , "Purveyor of meats" , "Spoil terribly" , "In EastEnders, Pat maybe" .)