Red roses are really expensive, initially (4)
I believe the answer is:
rare
'red' is the definition.
(thesaurus)
'roses are really expensive initially' is the wordplay.
'initially' indicates taking the first letters.
The first letters of 'roses are really expensive' is 'RARE'.
(Other definitions for rare that I've seen before include "Infrequent like underdone meat" , "Not well done!" , "Unusual(ly fine)" , "Unusual - exquisite" , "like Ben Jonson, Jack Young thought" .)