to make great efforts to achieve sth or do sth well :
He's working at losing weight.
Learning to play the piano isn't easy. You have to work at it .
to make great efforts to achieve sth or do sth well :
He's working at losing weight.
Learning to play the piano isn't easy. You have to work at it .
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005