Hidden difficulty is a term used to describe a situation that is not immediately apparent, but can cause problems if not addressed. The four crossword solutions for this term are SNAG (4 letters), PITFALL (7 letters), CATCH (5 letters) and JOKER (5 letters). SNAG refers to an unexpected obstacle or problem, while PITFALL is a hidden danger or trap. CATCH is a trick or snare, and JOKER is a person or thing that causes trouble or confusion. All of these words refer to the concept of hidden difficulty, which can be difficult to identify and address.