Mooncow, for 1d, if you reverse the answer and add two letters at the start, you get a word that can mean “rising more steeply”. For 4d, if you double up the vowel in the answer, you get the name of a famous golf course on the west coast of Scotland (which I was lucky enough to play the day before this puzzle was published). The fifth letter of the prototype comes from 6d
I also was flummoxed by 1a, which was my LOI. I would join any others in grumbling about that definition, but we’re quibbling