Help when a white rabbit ultimately turned on Alice? (9)
I believe the answer is:
cooperate
'help' is the definition.
(I've seen this before)
'a white rabbit ultimately turned on alice?' is the wordplay.
'ultimately' suggests the final letters.
'turned' says the letters should be written backwards.
'on' means one lot of letters go next to another.
'alice?' becomes 'Cooper' (Alice Cooper).
The last letters of 'white rabbit' are 'et'.
'et' backwards is 'te'.
'a'+'te'='ate'
'ate' after 'cooper' is 'COOPERATE'.
'when' acts as a link.
(Other definitions for cooperate that I've seen before include "Work constructively with others" , "band together" , "getting act together" , "Help" , "Play ball with" .)