Nothing right in girl? That's hard! (5)
I believe the answer is:
ivory
'that's hard' is the definition.
I can't judge whether this defines the answer.
'nothing right in girl?' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'right' becomes 'r' (common abbreviation).
'in' indicates putting letters inside.
'girl?' becomes 'ivy' ().
'o'+'r'='or'
'or' inserted into 'ivy' is 'IVORY'.
Can you help me to learn more?
(Other definitions for ivory that I've seen before include "Off-white colour" , "Smooth material of elephant tusks" , "Substance in elephant tusks" , "Some hunt this" , "Like the tower" .)