Correct

插足

/ chāzú /
Strokes

Definition

to squeeze in/to step in/to take part/to step between (two persons in a relationship)

Example

As a Verb

have a foothold in; set foot in; put one's foot in

1
Dào
道路
yòu
zāng
yòu
nìng
泥泞
  
,
méiyǒu
没有
chā
插足
de
fāng
地方
  

The road is dirty and muddy. It's hard to set foot in it.

As a Verb

participate/partake in; take part in; get involved in

2
Zài
zhīdào
知道
zhēnshí
真实
qíngkuàng
情况
zhīqián
之前
  
,
yìng
chā
插足
shì
此事
  

Before knowing the truth, you shouldn't get involved in it.

3
Yóu
由于
sānzhě
第三者
chā
插足
  
,
hūn
离婚率
zhúnián
逐年
shàngshēng
上升
  

The divorce rate is going up year by year as a result of marital infidelity.