Convene (3,8)
There are a few possibilities for this:
get together
(Other definitions for get together that I've seen before include "party" , "meeting" , "meet" , "social gathering" .)
'convene' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for gather that I've seen before include "Bring or come together in one place" , "Assemble or glean" , "Accumulate, amass" , "From information given, learn" , "Collect or assemble" .)
'convene' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for muster that I've seen before include "Assemble; rum set (anag.)" , "Gather or bring together" , "marshal" , "Assemble, gather together" , "Bring (troops) together" .)