Reddit reviews Designing Organic Syntheses: A Programmed Introduction to the Synthon Approach

https://www.amazon.co.uk/Organic-Synthesis-Disconnection-Stuart-Warren/dp/0470712368

I think this is the one I have, it's definitely by Warren anyway.

Edit:

https://www.amazon.co.uk/Designing-Organic-Syntheses-Programmed-Introduction/dp/0471996122

This is the one I have, you might have to shop around to find it a bit cheaper. I think I ended up with the Indian edition or something.

Also this one is pretty nice since you can work through it from the beginning to the end and afterwards you'll understand retrosynthesis.

You can find pdfs of it on the internet.

Organic Chemistry by John McMurray is very very good if you haven't got it already, I had this before I got Clayden and I found it a little easier when starting off.

Also, if you feel like a challenge a great question book to get is: Designing Organic Synthesis by Stuart Warren. It's a question text book that teaches you how to break down large molecules into easily synthesizable subunits and is invaluble for any synthetic course.