Reform hard, and for EU, without precedent (7-2)
I believe the answer is:
unheard-of
'without precedent' is the definition.
(I've seen this in another clue)
'reform hard and for eu' is the wordplay.
'reform' indicates an anagram (letters in a new form).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'h'+'and'+'for'+'eu'='handforeu'
'handforeu' with letters rearranged gives 'UNHEARD-OF'.
(Other definitions for unheard-of that I've seen before include "Not previously known or done - inaudible?" , "Fear hound being not previously known" , "Inconceivable" , "Unknown - novel" , "Without precedent" .)