close in
[verb]
Synonyms: enclose, cage, coop, corral, envelop, fence, hedge, hem, immure, mew

[TahlilGaran] English Synonym Dictionary ▲

close in phrasal verb (see also close)

1. to move closer to someone or something, especially in order to attack them:
The snake closed in for the kill.
close in on/around/upon etc
enemy soldiers closing in on them from all sides

2. if the night, bad weather etc closes in, it becomes darker or gets worse:
The sun had set and dusk was closing in.

3. if the days close in, they become shorter because it is autumn

[TahlilGaran] Dictionary of Contemporary English ▲

close in
v. To come in nearer from all sides.
We wanted the boat to reach shore before the fog closed in.
■ Often used with "on".
The troops were closing in on the enemy.

[TahlilGaran] English Idioms Dictionary ▲