Joint invitation to cheer (3)
I believe the answer is:
hip
'joint' is the definition.
(part of body)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for hip that I've seen before include "Fruit of a rose plant" , "Haunch" , "Trendy bodily joint?" , "In slang, trendy or stylish like body joint" , "Pelvic joint" .)