idioms

a lone wolf (a person who likes to work or live alone) Although John is a lone wolf, we all like him very much. Nobody knows much about him; he’s rather a lone wolf.   lone wolf – English Vocabulary

  get your brain in gear (make yourself start to think in a clear and effective way so that you can deal with something) I have to get my brain in gear for this important exam. Get your brain in gear because we have to finish the project on time. …

cudgel your brains  Old-Fashioned British English (think very hard) I have to cudgel my brains to find a solution. You should cudgel your brains to remember the address.   cudgel your brains – English Vocabulary

brain trust (a group of people with special knowledge who advise a leader) He is a member of the president’s brain trust. He gathered a useless brain trust around himself.   brain trust – English Vocabulary

  brainwave  British English (a clever idea) I’ve just had a brainwave; we should leave the car here. Unless you have a brainwave, we’ll never finish the work on time.     brainwave – English Vocabulary