Call on six to be seated (5)
I believe the answer is:
visit
'call on' is the definition.
('visit' can be a synonym of 'call on')
'six to be seated' is the wordplay.
'six' becomes 'vi' (roman numeral).
'to be seated' becomes 'sit' (I've seen this before).
'vi'+'sit'='VISIT'
(Other definitions for visit that I've seen before include "Drop in; frequent" , "Come to see" , "Call on (someone)" , "Go to see a place or person" , "Call upon" .)