Certify to be at the cricket match (6)
I believe the answer is:
attest
'certify' is the definition.
(I know that certify can be written as attest)
'at the cricket match' is the wordplay.
'the cricket match' becomes 'test' (a test is a kind of cricket match).
'at'+'test'='ATTEST'
'to be' is the link.
(Other definitions for attest that I've seen before include "Declare (that something is the case)" , "Provide firm evidence" , "Give sworn evidence" , "Corroborate" , "Bear witness, declare to be true" .)