Sometimes quiz clues can be a little bit loose - and if 'sedge' is really sledge and if 'good' is redundant in 27 it might be worth considering these:
9 - BANKING ? (another word for 'hilling'/'earthing' potatoes) it almost works as a double defintion clue - 'taking things into account' and what a pond skater (insect) would be doing if it wasn't in the water.
18 - ROLLING HARROW ? (used to level a field) 'rolling' = drunk, but Harrow is a College or a University campus, not a University.
Worth a shot if nothing better comes along, BenCotto - good luck with it.