Mark’s US partner, beautiful to see (4,5)
I believe the answer is:
fair catch
'mark's' is the definition.
(I've seen this before)
'us partner beautiful to see' is the wordplay.
I cannot quite understand how this works, but
'partner' could be 'catch' (I have seen 'Desirable partner' mean 'catch' so perhaps 'partner' could also mean 'catch') and 'catch' is present in the answer.
'beautiful' could be 'fair' (similar in meaning) and 'fair' is found within the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for fair catch that I've seen is " Mark".)