Based on the clue 'a flatbed or pickup for a mallard', what is the answer?

Based on the clue 'a flat surface on which outdoor advertisements are...', what is the answer? Based on the clue 'a flat thin metal ring used between a bolt a nut ...', what is the answer? Based on the clue 'a flat topped mountain with steep sides its from s...', what is the answer? Based on the clue 'a flatbed one of these optical devices is used to ...', what is the answer? What is referred to by 'a flavorful gherkin'? Based on the clue 'a flaw in some pictures here its used for artistic...', what is the answer? Based on the clue 'a flaw or to switch sides', what is the answer? Based on the clue 'a flea hath smaller fleas that on him prey and t...', what is the answer?