The phrase "a practice which" is correct and usable in written English.
It can be used to introduce a specific practice or method that is being described or explained.
Example: "Meditation is a practice which helps individuals reduce stress and improve focus."
Alternatives: "a method that" or "a technique which".
Most of the men had themselves tattooed, some had had their entire backsides blacked, a practice which bestowed much prestige.
Hers is also a practice which habitually "frays out into other art forms, in this case film".
However in an April referendum this year, Maltese voters approved the controversial spring hunting of migratory birds - a practice which is illegal throughout the rest of the EU.
The FA Cup will find a number of managers, McCarthy probably among them, diluting their teams with reserves, a practice which continues to devalue the tournament.
It is the last hurrah of FAT, a practice which for two decades made an art out of opposing received wisdom.
But the cabin crew were reassuring and soothing music was played during take-off and landing, a practice which should, I think, be adopted industry-wide.
It's a practice which a considerable number of high profile and successful firms, including Lego, Volvo and AstraZeneca, are interested in, and have joined the Beyond Budgeting Institute.
Latin proverbs were used in translation exercises, a practice which drummed them into the minds of students, who then took them out into the world.
Lifting weights – a practice which helped develop some of the most fearsome biceps and powerful groundstrokes in women's tennis – went out the window in favour of more running.
The organisation says objectifying women on the pages of the tabloid, a practice which has gone on for more than 40 years, is "disrespectful" and sexist.
Officials insisted that Britain would not cooperate in a practice which could leave it open to the charge it was conniving in torture.
