Fruit a madman may be out of! (5)
I believe the answer is:
gourd
'fruit a madman' is the definition.
'gourd' can be an answer for 'fruit' (I've seen this before). I am not sure about the 'a madman' bit.
'be out of' is the wordplay.
'be' becomes 'go' (going is a kind of being).
'out of' becomes 'urd' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'go'+'urd'='GOURD'
'may' acts as a link.
Can you help me to learn more?
(Other definitions for gourd that I've seen before include "Hard-skinned fruit" , "Hard-rinded fruit often used as container" , "Large fruit" , "Bottle, dishcloth, plant" , "Fruit akin to pumpkin" .)