Small milliner gets break (7)
I believe the answer is:
shatter
'break' is the definition.
(to break can mean to shatter)
'small milliner' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'milliner' becomes 'hatter' (synonyms).
's'+'hatter'='SHATTER'
'gets' is the link.
(Other definitions for shatter that I've seen before include "Break suddenly" , "Crack" , "Completely upset" , "Break the minister into little pieces" , "Threats (anag.)" .)