Someone who is single-minded has only one aim or purpose and is determined to achieve it.
例句
They were effective politicians, ruthless and single-minded in their pursuit of political power.他们都是些非常现实的政治家，一心追逐政治权力，为达目的毫不留情。...a single-minded determination to win.一心要赢
英英词典释义
Adjective
1. determined;
"she was firmly resolved to be a doctor""single-minded in his determination to stop smoking"