Sign political group follows to close down online presence (6)
I believe the answer is:
logoff
'down online presence' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'sign political group follows to close' is the wordplay.
'sign' becomes 'logo' (logo is a kind of sign).
'political group follows' becomes 'ff' (I can't justify this - if you can you should believe this answer much more).
'to close' says to put letters next to each other.
'logo'+'ff'='LOGOFF'
Can you help me to learn more?
(Other definitions for logoff that I've seen before include "Leave Internet session" , "End computer session" , "Terminate (computer session)" .)