Southampton have made their opening bid for a player Russell Martin is keen to sign, but a deal could be ‘tricky’. Russell Martin will have spent the off-season identifying the areas of his Southampton squad he needs to improve this summer. The free signing of veteran Adam Lallana is an astute piece of business but he is so far the only new arrival at St Mary’s; Taylor Harwood-Bellis signing permanently but having spent last season on loan at the club. So far this summer Southampton’s focus has been on trying to sign Premier League experience for free, with Saman Ghoddos, Charlie Taylor and Bo…