Regularly sell out in advance of John B Keane play - it's hard to catch (7)

I believe the answer is:

elusive

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'hard to catch' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for elusive that I've seen before include "Vile Sue, not easy to find" , "Difficult to find or catch" , "Difficult to catch or see" , "Evil use (anag.)" , "Use veil to be difficult to catch" .)

I've seen this clue in The Irish Times.

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