Crazy about mother (3)
I believe the answer is:
mad
'crazy' is the definition.
(I know that crazy can be written as mad)
'about mother' is the wordplay.
'about' is a reversal indicator.
'mother' becomes 'dam' (female parent of an animal).
'dam' backwards is 'MAD'.
(Other definitions for mad that I've seen before include "Extremely foolish" , "Crazy" , "Demented or excited or angry" , "Insane - furious" , "Frenzied" .)