Mean about a single flower (7)
I believe the answer is:
anemone
'flower' is the definition.
(I know that anemone is a type of flower)
'mean about a single' is the wordplay.
'about' indicates anagramming the letters.
'a single' becomes 'one' (a single thing - only one).
'mean' is an anagram of 'anem'.
'anem'+'one'='ANEMONE'
(Other definitions for anemone that I've seen before include "The flower is no enema" , "Tentacled sea dweller, flower" , "Bright flower or sea plant" , "White woodland flower" , "Plant; marine creature" .)