Crazy chap, is it? Character resembling a football nut (9)
I believe the answer is:
pistachio
'a football nut' is the definition.
'pistachio' can be an answer for 'nut' (pistachio is a kind of nut). I'm not certain of the 'a football' bit.
'crazy chap is it? character' is the wordplay.
'crazy' indicates an anagram.
'character' becomes 'o' ().
'chap'+'is'+'it'='chapisit'
'chapisit' with letters rearranged gives 'pistachi'.
'pistachi'+'o'='PISTACHIO'
'resembling' acts as a link.
Can you help me to learn more?
(Other definitions for pistachio that I've seen before include "Nut tree" , "Edible pale green seed" , "Food" , "nut-bearing tree" , "Type of nut" .)