“Haven’t the foggiest!” … or, when the first two letters are put at the end, an essential part of seven answers in this puzzle Crossword Clue

 The answer to the crossword clue "“Haven’t the foggiest!” … or, when the first two letters are put at the end, an essential part of seven answers in this puzzle" is DUNNO.

The phrase "haven't the foggiest" means "I don't know." When the first two letters "d" and "u" are put at the end, the word becomes "nodd," which is a verb meaning "to move the head up and down in a gesture of assent or agreement."

The seven answers in the puzzle that contain the word "nodd" are:

nod (verb)

nodded (past tense of nod)

nodding (present participle of nod)

noddingly (adverb)

nodulation (the act of nodding)

nodulous (having a small, rounded lump)

nodulousness (the quality of being nodular)

nodule (a small, rounded lump)

I hope this helps!