Singular fruit with perfect flavour (9)
I believe the answer is:
spearmint
'flavour' is the definition.
(I've seen this before)
'singular fruit with perfect' is the wordplay.
'singular' becomes 's' (abbreviation sometimes used in dictionaries).
'fruit' becomes 'pear' (pear is a kind of fruit).
'with' is a charade indicator (letters next to each other).
'perfect' becomes 'mint' (similar in meaning).
's'+'pear'+'mint'='SPEARMINT'
(Other definitions for spearmint that I've seen before include "Strongly flavoured herb" , "Aromatic herb" , "Aromatic plant" , "Herb used for flavouring" , "Garden flavouring" .)