Journalist Adrian Clarke believes that Arsenal must find an upgrade on one current regular starter if they are to achieve Champions League glory in the future. Arsenal reached the quarter-final stage of the Champions League this season for the first time in 14 years, before being ejected from the competition at the hands of Bayern Munich. Mikel Arteta will be desperate for his side to improve their showing in Europe next season. There is no reason why this Arsenal side, who are now genuine Premier League title contenders, shouldn’t be eyeing up glory in Europe’s elite club competition. Arteta …