expression
single-handedly (of a man raising children); on one's own; as a single father
Fixed expression used when a man raises children alone, often followed by 育てる. Implies doing it without a partner's help.
See also: 女手一つで
彼は男手一つで三人の子供を育てた。
He raised three children single-handedly as a father.
男手一つで家事も仕事もこなしている。
He manages both housework and his job on his own as a single father.
The female counterpart, meaning a woman raising children alone.
Compound of 男手 (man's hand/labor) + 一つ (one) + で (by means of), literally 'with one man's hand'.