Person using ticket in response to offer (8)
I believe the answer is:
attender
'person' is the definition.
(attender is a kind of person)
'ticket in response to offer' is the wordplay.
'ticket in response' becomes 'at' (I can't explain this - if you can you should believe this answer much more).
'to offer' becomes 'tender' (tender can mean to offer something).
'at'+'tender'='ATTENDER'
'using' is the link.
Can you help me to learn more?
(Other definitions for attender that I've seen before include "someone present" , "An individual present" , "One present" , "listener" , "who's present?" .)