Final high-ranking card - it's played on Judgement Day (4,5)
I believe the answer is:
Here is my best explanation:
'played on judgement day' is the definition.
(trumpet blast that wakes the dead on judgement day)
'final high-ranking card' is the wordplay.
'final' becomes 'last' ('last' can be a synonym of 'final').
'high-ranking card' becomes 'trump' (e.g. in bridge or whist).
'it's' is the link.