"practice designed" is correct and usable in written English.
You would use it when referring to a specific action or activity that has been specifically designed to improve a skill or for a particular purpose. For example, "The practice designed to help us improve our public speaking skills was challenging but ultimately effective."
The cultural practice, designed to ensure girls' virginity, can lead to excessive bleeding, infection, infertility and death.
Salzberg is a proponent of metta or "loving-kindness" meditation, a practice designed to cultivate compassion for all living beings.
This is a practice, designed to avoid illustration of the music, that is common to modern dance but not to the ballet world.
Turnbull was a devout Baptist and the practice designed two churches, in Wye Street, Battersea, and at Waterlooville, Hampshire, before his early death.
The coalition government is never happier than when it finds a policy or practice designed by Labour to be "not fit for purpose", and perhaps this is how it considers the DHP funding stream.
Deliberate interference such as the jamming of transmissions is a blatant violation of international regulations concerning the use of satellites and we strongly condemn any practice designed to disrupt audiences' free access to news and information.
Or the Royal Marines' decision to name their action against Basra "Operation James" in the latest war on Iraq, with military targets code-named "Goldfinger," "Blofeld" and "Connery" -- a practice designed to "give morale a boost"?
In some schools, grades for advanced placement and honors classes are worth a point or more toward G.P.A. than are grades for standard classes, a practice designed to reward and motivate students to take challenging material.
Mr. Mukasey overturned a decades-old practice designed to ensure robust constitutional protection for immigrants — one needed now more than ever in the days of the Bush administration's assembly-line prosecutions.
