have a crush on somebody
to love and be sexually attracted to someone you are not having a relationship with, usually someone older
have a crush on someone
to have strong feelings of love for someone (often for a short time and with no results), to be attracted to someone

[TahlilGaran] English Idioms Dictionary ▲

have a crush on someone
• have a crush (on someone)
to have strong feelings of love for someone (often for a short time and with no results); to be attracted to someone
The young girl had a crush on her teacher in junior high school but of course it was an impossible situation.

The girl has a crush on someone at her university.

[TahlilGaran] English Idioms Dictionary ▲