to place something, such as money, into reserve; to store something in a secure place. I try to sock a little money away each month for my vacation. I will sock away some money.
Put money in a safe place for future use, as in I've got about $2,000 socked away for a new car. This usage presumably alludes to putting one's savings in a sock. [Colloquial; first half of 1900s]
To put something valuable in a safe place for future use: He socked away some gold in a mattress in case the bank was robbed. While the rest of us have been blowing our salaries on electronic gadgets, she has been quietly socking hers away.