I personally don't find that a glaze or icing adds much in terms of flavours other that sweetness but you can absolutely make one if you like sweeter desserts! You can make a classic lemon drizzle by mixing powdered sugar (or icing sugar) with a little bit of lemon juice. Alternatively, for a stronger lemon taste, make a lemon syrup by reducing some lemon juice with sugar in a small saucepan.