Anxious batting certain to entertain most of ECB (8)
I believe the answer is:
insecure
'anxious' is the definition.
('insecure' can be similar in meaning to 'anxious')
'batting certain to entertain most of ecb' is the wordplay.
'batting' becomes 'in'.
'certain' becomes 'sure' ('sure' can be a synonym of 'certain').
'to entertain' means one lot of letters goes inside another.
'most of' means to remove the last letter.
'ecb' with its last letter removed is 'ec'.
'sure' placed around 'ec' is 'secure'.
'in'+'secure'='INSECURE'
(Other definitions for insecure that I've seen before include "Defenceless" , "Wavering" , "Fearful, unsafe." , "open to attack" , "Timid" .)