Mix game and social media word (7)
I believe the answer is:
hashtag
'mix' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'game and social media word' is the wordplay.
'game' becomes 'tag' (children's playground game).
'and' is a charade indicator (letters next to each other).
'social media word' becomes 'hash' (I am not sure about this - if you are sure you should believe this answer much more).
'tag' put after 'hash' is 'HASHTAG'.
Can you help me to learn more?
(Other definitions for hashtag that I've seen before include "Octothorp" , "Label on a tweet" , "Number symbol" , "component of tweet" , "Twitter mark" .)