Devise (verb)
From Hull AWE
The verb 'to devise' is one of those verbs ending in the sound 'EYES' (IPA: /aɪz/) for which, despite the advice in -ise - -ize, the spelling with -ise "is compulsory" (Burchfield's Fowler, s.v. -ise).
You may also want to see AWE's advice on the difference between devise and device.