fall to
[verb]
Synonyms: pitch in, buckle (down), jump (in or into), set to, wade (in or into)

[TahlilGaran] English Synonym Dictionary ▲

fall to somebody/something phrasal verb (see also fall)

1. if a duty or job falls to someone, they are responsible for doing it, especially when this is difficult or unpleasant:
It fell to me to give her the bad news.

2. written to start doing something:
They fell to work with a will.
fall to doing something
He fell to thinking about how nice a warm bath would be.

[TahlilGaran] Dictionary of Contemporary English ▲

fall to
v.
1. To begin to work.
The boys fell to and quickly cut the grass.
Synonym: TURN TO.
2. To begin to fight.
They took out their swords and fell to.
3. To begin to eat.
The hungry boys fell to before everyone sat down.
4. Begin; start.
The old friends met and fell to talking about their school days.

[TahlilGaran] English Idioms Dictionary ▲