Really struggling with this one. May just throw it. I'm only half done
7a the kind of craft in which tennis-players try to excel (5) -o---
10a volley of shots from widely spread team (9) 6th letter is S
15a The maxim of immortal optimism/ (5,3,3) -----/s--/-i-
17a Producing memoirs about one's vocation (9) 6th letter is L
That may help to get me going again