I found this deal a few days ago.
After looking for the Clarks Olso Beth online and in stores in a size 5.5 (sold out on clarks.com and in my local shops) They reduced them initially to £63.99 from £70.00, when I bought them on friday, but they reduced them once more down to £59.49.
That in itself is a great offer, but if you're a new customer you can get 15% off by signing up to their newsletter, if you spend a minimum of £75 , get 10% cashback from Topcashback and free delivery.
Zalando has a huge selection of reduced items (incl. other Clarks and other brands and not just shoes) so I'm sure you could easily reach the £75 or just leave it at the £59.49 and get the 10% cashback :-)