Definition: "benefit"

This is a charade combined with deletion - you need to remove a letter from one word, then add another word to it.

Take 'youngster' and remove the letter that represents 'year', then add 'on' to get your answer.

Answer: BOON | Take BOY ('youngster'), remove Y ('year' - this is what 'spends' indicates), giving you BO, then add ON to get BOON (benefit).