Turned up to vet, a step towards getting a mate? (10,5)
I believe the answer is:
discovered check
'a step towards getting a mate?' is the definition.
(chess term)
'turned up to vet' is the wordplay.
'turned up' becomes 'discovered' (to turn something up is to discover it).
'to vet' becomes 'check' (vet can mean to test or check).
'discovered'+'check'='DISCOVERED CHECK'
(Other definitions for discovered check that I've seen before include "Threat caused by removing obstruction" , "threat to the king" , "threat to man on board" , "Attack on king" , "result of a move on board" .)