Yelow leaf a deformed top

Yellow leaves down low on plants flowering are pretty normal and not a whole lot to worry about. The reason they go yellow, apart from being a long way from your light, is that the plant will use elements that are in the older for re-use in the growing of the flowers, as it is more efficient to do so, rather than grow flowers AND make these growth elements (carbs, sugars, amino acids etc) from new. Therefore, by defoliating your plant, not only do you reduce her capacity to make energy for growth, you also rob her of this important "stash" of vital growth elements that she needs for growing her biggest and best flowers. As it is now, she must now divide her energy between growth and re-synthesizing these vital growth elements from new, rather than just using energy for growth alone. Rather tan defoliating, try and only remove yellow leaves, for by the time they are yellow, they have served their purpose, of either being energy makers or a "stash" of premade nutrition. The upper portion of your plant seems to be a combination of too much heat and not enough ventilation, which is the ultimate cause of the excessive heat. As your plant is still very early in flowering, it is not too late to tie the long main stem down somewhat to a more horizontal position and further away from the light, thereby hopefully resolving the heat and ventilation problem that is occurring in the top corner of your tent. Hope this helps,........... Organoman.