Expecting what’s required for defence in test (8)
I believe the answer is:
enceinte
'expecting' is the definition.
(both can mean pregnant)
'required for defence in test' is the wordplay.
'required for' says the answer is hidden in the clue.
'ENCEINTE' is hidden within 'defence in test'.
'what's' acts as a link.
(Other definitions for enceinte that I've seen before include "enclosure" , "Like a woman expecting" , "some fortification" .)