Nedarim 88b - Giving a limited gift

The gemara discusses whether and how one can limit a gift given to a woman to prevent her husband from being zocheh in it. The Ran on the mishna (second peshat) understands even according to R' Meir that her hand is like her husbands, one can limit the gift he gives her to specific activities to prevent her husband from acquiring it. Similarly, in the end of the gemara the Ran explains the opinion of the Rambam that if one gives a gift to a woman "on the condition that her husband is not zocheh in it, and that she can do what she wants with it", the clause of being able to do what she wants with it implies that it is not an absolute gift, rather he is giving her limited ownership so that she can slowly decide what she wants to spend each dollar on, so the husband is not zocheh in it. The entire discussion of what type of language is necessary to prevent the gift from being absolute, is because by default the gift will be absolute. But when we have an umdana that the gift is for a specific purpose, it is not considered "owned" by the receiver to use if for another purpose.
R' Moshe (Y.D. 2:112) has a similar approach to explain that when a father in-law gives money to his son in-law for living expensed to enable him to learn comfortably in kollel, the son in-law is not entitled to give 10% as ma'aser on that money because it is not an absolute gift, rather it is for the specific purpose of his living expenses. R' Moshe writes:

אבל הנדוניא הניתן לצורך כגון הכא שהעשרת אלפים ניתנו כדי שיהיה חתן פנוי ללמוד בכולל במנוחה, תלוי בדעת הנותן דלא היה נותן להם לחלק מזה לאחרים אף לא לצדקה ואין יכול לשנות מדעת הנותן, וכיון שחותנו אומר שניתן רק בשביל שיהיה פנוי ללמוד והחתן אינו מכחישו אין לו רשות לחלק אף המעשר מהם אף לא לצדקה