Answer: thinkingcap

AnswerCrossword Clue
THINKINGCAPSymbol of concentration
THINKINGCAPThis is "put on" to solve a problem
THINKINGCAPContemplation aid
THINKINGCAPFiguratively, a mood of reflection.
THINKINGCAPCogitative gear.
THINKINGCAPMind at work.
THINKINGCAPSymbol of deep concentration
THINKINGCAPProblem-solving accessory
THINKINGCAPInvisible symbol of concentration