1. phrasal verb
If someone hushes something up, they prevent other people from knowing about it. [V n P] ⇒ The scandal has been discussed by the politburo, although the authorities have tried to hush it up. [V P n] ⇒ The Ministry desperately tried to hush up the whole affair.
2. phrasal verb → hush If people in authority hush someone up, they try to stop that person revealing information which they want to keep secret. [V n P] ⇒ The Conservative Government was only too quick to hush him up.
COBUILD Advanced English Dictionary. Copyright © Harper Collins Publishers