molba

1. request; plea
   Imam jednu molbu za tebe. — I have a favour to ask you.
   Nije hteo da usliši našu molbu. — He wouldn't grant our request.
2. (formal, written) application; written request
   Predala sam molbu za godišnji odmor. — I submitted a request for annual leave.

The thing asked for is introduced with «za» + acc.: «molba za pomoć».