Complex sentence: Charles Walder Grinstead (1860-1930) was an English champion tennis player who, with C. E. Weldon, won the Oxford Men's Doubles in 1883.
Split into simpler sentences: Charles Walder Grinstead (1860-1930) was an English champion tennis player. Together with C. E. Weldon, Grinstead won the Oxford Men's Doubles in 1883.