Extend the house and cheer wildly (5,3,4)
I believe the answer is:
raise the roof
'extend the house' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for raise the roof that I've seen before include "Make a great commotion" , "Extend the house" , "cause a massive disturbance?" , "Make a lot of noise" , "make merry!" .)