Modernises cheerful appointments (7)
I believe the answer is:
updates
'modernises' is the definition.
(I've seen this in another clue)
'cheerful appointments' is the wordplay.
'cheerful' becomes 'up' (up can mean cheerful or upbeat).
'appointments' becomes 'dates' ('date' can be a synonym of 'appointment').
'up'+'dates'='UPDATES'
(Other definitions for updates that I've seen before include "latest reports" , "Brings to current status" , "Modernises" , "Fresh bulletins" , "Revises to current status" .)