Dic: settle down to (do) something

• He got his coffee, came back and settled down to listen. 
• They settled down to some serious work. 
• They finally settled down to a discussion of the main issues.
• He found it hard to settle to his work. 
• I settled down to read about the festival and what I could do there.

1. PHRASAL VERB | If you settle down to do something or to something, you prepare to do it and concentrate on it.

2. settle (down) to something: to begin to give your attention to something.

3. settle down to something: to give something all of your attention.

cf. Usage notes: often said about a meal: 

• After work, we all settle down to a home-cooked dinner.

.... Cobuild, OALD, Cambridge Dictionary of American Idioms