Single point about single fool (5)
I believe the answer is:
idiot
'fool' is the definition.
(synonyms)
'single point about single' is the wordplay.
'single' becomes 'I' (one).
'point' becomes 'dot' (synonyms).
'about' means one lot of letters goes inside another.
'single' becomes 'I' (one).
'dot' going around 'i' is 'diot'.
'i'+'diot'='IDIOT'
(Other definitions for idiot that I've seen before include "'The -----'. novel by Dostoyevsky (1868)" , "Silly ass" , "Fool, silly person" , "Garret" , "Unwise person" .)