Experts employed in court battles (4)

I believe the answer is:

aces

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'experts' is the definition.
(ace is a kind of expert)

I don't understand the rest of the clue.

(Other definitions for aces that I've seen before include "They're high and low on cards" , "Case of top cards" , "Champions" , "Two will make deuce" , "holes in one" .)

I've seen this clue in The Irish Independent.

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