Bear witness at cricket match (6)
I believe the answer is:
attest
'bear witness' is the definition.
(synonyms)
'at cricket match' is the wordplay.
'cricket match' becomes 'test' (a test is a kind of cricket match).
'at'+'test'='ATTEST'
(Other definitions for attest that I've seen before include "Verify" , "Declare (that something is the case)" , "Act as witness" , "Demonstrate" , "Vouch for" .)