Complex sentence: Smith spent much of his childhood in Angus but, after showing great footballing promise playing for Montrose Roselea and Dundee North End, was to return to Edinburgh to pursue a career as a professional.
Split into simpler sentences: Smith spent much of his childhood in Angus and showed great footballing promise playing for Montrose Roselea and Dundee North End. Smith was to return to Edinburgh to pursue a career as a professional.