založiti

1. to pawn; to mortgage; to put up as collateral
   Založio je zlatni sat da plati kiriju. — He pawned his gold watch to pay the rent.
   Založili su kuću da bi dobili kredit. — They mortgaged the house to get a loan.
2. (založiti se za + acc.) to stand up for; to advocate; to put in a word for
   Direktor se lično založio za mene. — The director personally put in a word for me.
   Stranka se založila za niže poreze. — The party came out in favour of lower taxes.
3. colloq. to have a bite; to have a snack
   Hajde da založimo nešto pre puta. — Let's have a bite before we set off.
4. (of a fire or stove) to stoke; to light
   Založi peć, hladno je. — Stoke the stove, it's cold.
5. (založiti se) to put in effort; to give one's all; to try hard
   Igrači su se maksimalno založili u drugom poluvremenu. — The players gave their all in the second half.
   Ako se založiš, položićeš ispit. — If you put in the effort, you'll pass the exam.

In the senses 'stand up for' and 'put in effort' it is reflexive: založiti se (za + acc.).