a cloud on the horizon
US /ə klaʊd ɑn ðə ˈhaɪ.rɪ.zən/
UK /ə klaʊd ɑn ðə ˈhaɪ.rɪ.zən/

1.
隐忧, 潜在问题
a potential problem or difficulty that may arise in the future
:
•
Despite the current success, there's a cloud on the horizon regarding the company's future funding.
尽管目前取得了成功,但公司的未来融资方面仍有隐忧。
•
The new regulations cast a cloud on the horizon for small businesses.
新规定给小企业带来了隐忧。