Dimwit (4)
(Other definitions for boob that I've seen before include "Blunder (colloq.)" , "Mistake; breast (sl.)" , "Embarrassing mistake" , "Error" , "Slip" .)
'dimwit' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for dolt that I've seen before include "Dunce" , "Dull or stupid fellow" , "Fool" , "Dullard" , "Slow-witted person" .)
'dimwit' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Another definition for simp that I've seen is " who is easily imposed upon?".)