Complex sentence: Frank Smith was a professional rugby league footballer who played in the 1930s, and 1940s, playing at representative level for Yorkshire, and at club level for Castleford, and Dewsbury, as a, i.e. number 11 or 12, during the era of contested scrums.
Split into simpler sentences: Frank Smith was a professional rugby league footballer who played in the 1930s, and 1940s. He played at representative level for Yorkshire, and at club level for Castleford, and Dewsbury, as a, i.e. number 11 or 12, during the era of contested scrums.