Attendance making ticket seller accept vase (7)
I believe the answer is:
turnout
'attendance' is the definition.
(turnout is a kind of attendance)
'ticket seller accept vase' is the wordplay.
'ticket seller' becomes 'tout' (as in a ticket tout).
'accept' means one lot of letters goes inside another.
'vase' becomes 'urn' (both can mean a container).
'tout' going around 'urn' is 'TURNOUT'.
'making' is the link.
(Other definitions for turnout that I've seen before include "Attendance figure" , "Number of people who come to a function, or their dress" , "The number of people who came to a function" , "assembly" , "number of people present" .)