Leave social networks, anticipating trouble (3,4)
I believe the answer is:
set sail
'leave' is the definition.
(I've seen this before)
'social networks anticipating trouble' is the wordplay.
'social networks' becomes 'sets'.
'anticipating' says to put letters next to each other.
'trouble' becomes 'ail' ('ail' can be a synonym of 'trouble').
'sets'+'ail'='SET SAIL'
(Other definitions for set sail that I've seen before include "have started journey" , "Embark on a voyage by ship" , "Begin a voyage" , "Left port" , "Leave for (sea) voyage" .)