Convivial rogues messing about in Riga (10)
I believe the answer is:
gregarious
'convivial' is the definition.
Both the definition and answer are adjectives. Perhaps there's a link between them I don't understand?
'rogues messing about in riga' is the wordplay.
'messing' indicates anagramming the letters (I've seen 'mess' mean this).
'about' is an insertion indicator.
'in riga' becomes 'gari' (I can't explain this - if you can you should give a lot more credence to this answer).
'rogues' is an anagram of 'greous'.
'greous' enclosing 'gari' is 'GREGARIOUS'.
Can you help me to learn more?
(Other definitions for gregarious that I've seen before include "Enjoying the company of others" , "Outgoing" , "Sociable" , "tending to flock" , "Living in flocks" .)