Wicket crosspiece (4)
I believe the answer is:
bail
'wicket crosspiece' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for bail that I've seen before include "Item resting on stumps" , "Horizontal piece of cricket wicket" , "Security for release from custody" , "small bar on field" , "Piece placed on top of cricket stumps" .)