23ac. No geek pens book in computer language. (5) C?B?L.
I think 24dn. is Bring and 17dn. is Sidelight. but I'm not quite sure how they fit the clues. The same applies to 7dn. which I think is Recognise.
Clues are 24dn. Take first of boats over sound.(5) 17dn. One shines, so shop is visible?.(9)7dn. See English troubadour getting high, inhaling joint.(9)