Fruit prohibition advice not accepted initially (6)
I believe the answer is:
banana
'fruit' is the definition.
(type of fruit)
'prohibition advice not accepted initially' is the wordplay.
'prohibition' becomes 'ban' (synonyms).
'initially' says to take the initial letters.
The first letters of 'advice not accepted' is 'ana'.
'ban'+'ana'='BANANA'
(Other definitions for banana that I've seen before include "that may be unzipped" , "Fruit grown in hands" , "Long curved fruit" , "plant" , "Yellow-skinned fruit" .)