Drop in and see everybody (4)
I believe the answer is:
call
'drop in' is the definition.
(thesaurus)
'see everybody' is the wordplay.
'see' becomes 'c' (the word for the letter, according to Chambers).
'everybody' becomes 'all' (I've seen this before).
'c'+'all'='CALL'
'and' acts as a link.
(Other definitions for call that I've seen before include "Visit; cry out" , "decision" , "That is enough" , "Ring or visit" , "Hail; visit" .)