Hole used to be hard? Rubbish! (7)
I believe the answer is:
eyewash
'rubbish' is the definition.
(both can mean nonsense)
'hole used to be hard?' is the wordplay.
'hole' becomes 'eye' (eye is a kind of hole).
'used to be' becomes 'was' (eg 'he was...' means 'he used to be...').
'hard?' becomes 'h' (abbreviation used in pencil classifications).
'eye'+'was'+'h'='EYEWASH'
(Other definitions for eyewash that I've seen before include "Balderdash" , "Visual cleansing agent - nonsense" , "Bunk" , "Pupils may benefit from this" , "Nonsense; cleansing lotion" .)