Hard toenails have broken hard bit of shower (9)
I believe the answer is:
hailstone
'hard bit of shower' is the definition.
(hard bit of a hail shower)
'hard toenails have broken' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'have broken' indicates an anagram.
'toenails' is an anagram of 'ailstone'.
'h'+'ailstone'='HAILSTONE'
(Other definitions for hailstone that I've seen before include "Hard precipitation" , "Small pellet of ice" , "Falling ice" , "Frozen pellet" , "bit icy" .)