To have an axe to grind (idiom):
English Meaning - To have a strong personal opinion about something that you want people to accept and that is the reason why you do something.
Bangla Meaning - (লাক্ষণিক) ব্যক্তিস্বার্থ থাকা।
Example Sentence - Environmentalists have no political axe to grind - they just want to save the planet.
More idioms,
To strain every nerve - To make the greatest possible effort.
To take heart - If you take criticism or advice to heart, you think about it seriously, often because it upsets you.
To draw the line - To never do something because you think it is wrong.
Source: Cambridge Dictionary.