Denies match official's welcoming cup-ties on a regular basis (7)
I believe the answer is:
refutes
'denies' is the definition.
(refute can mean to deny or reject)
'match official's welcoming cup-ties on a regular basis' is the wordplay.
'match official's' becomes 'ref's' (referee).
'welcoming' indicates putting letters inside (in sense of 'inviting in').
'on a regular basis' means one should take alternating letters.
'cup'+'ties'='cupties'
The alternate letters of 'cupties' are 'ute'.
'refs' enclosing 'ute' is 'REFUTES'.
(Other definitions for refutes that I've seen before include "Disproves" , "Proves (a statement) wrong" .)