Hi FemmeNoire,
15a - This is the clue with 2 theme words mentioned in the preamble so is 2 theme words + an anagram/"fresh" of "sea air" - definition is a word meaning "old inn for Eastern travellers".
16a - An anagram of 2 words in the clue + a theme word - definition is "those below stairs" (as in Upstairs Downstairs)
20d - Is a straight anagram - definition is "undertakings to be responsible".
40d - Is a humorous definition of the people who might need to count these "woolly jumpers" when they can't s????