Sentence:  Mercer 's Whiteman association brought him into contact with Hoagy Carmichael , whose `` Snowball '' Mercer relyriced as `` Lazybones '' , in which form it became a hit and marked the real beginning of Mercer 's song writing <WSD>career</WSD> . 
Meaning of the word marked with <WSD> tags:  the particular occupation for which you are trained