In a bowl, whisk together whole wheat flour, baking powder, soda and cloves; set aside.
In a large bowl, using electric mixer beat together margarine and brown sugar until fluffy. Beat in egg. Add bran and grapefruit juice and stir to combine. Add flour mixture and stir until well combined. Divide batter among 12 paper lined muffin tins and bake in 190°C (375°F) oven for about 20 minutes or until firm to the touch.
In a small bowl, stir together grapefruit juice and honey. Brush mixture on tops of warm muffins and let cool slightly before serving.