Reportedly cheer up seaside resort (8)
I believe the answer is:
brighton
'seaside resort' is the definition.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for brighton that I've seen before include "Sussex seaside resort" , "seaside location" , "English resort with big thorn" , "South-coast resort" , "Sussex coastal resort" .)