Superior forehand smashes outrageous (7,2)
I believe the answer is:
unheard of
'outrageous' is the definition.
(I've seen this in another clue)
'superior forehand smashes' is the wordplay.
'superior' becomes 'U' (U can mean upper-class, as in U and non-U speech).
'smashes' is an anagram indicator.
'forehand' with letters rearranged gives 'nheardof'.
'u'+'nheardof'='UNHEARD-OF'
(Other definitions for unheard of that I've seen before include "Very unusual" , "ignoring precedent" , "never seen before" .)