First, I'm with Tyler on this one; totally confused. I thought it was an assignment using those ingredients.
Second: If you should follow ChrisBelgium's idea, I would consider celeraic in the tagine, rather than hunks of celery. Keep in mind, too, that one hallmark of a good tagine is the broth. So use lots of the jus.
Actually, three comments. Regarding this: because my chef wants to make an herb rub instead under the chicken skin.
As you pursue both your culinary education and, later, once out in the field, remember this advice: If Chef tells you to do one thing, and God tells you to do another, you better pray that God is forgiving.