A singular and special fool (3)
I believe the answer is:
ass
'fool' is the definition.
(ass is a kind of fool)
'a singular and special' is the wordplay.
'singular' becomes 's' (abbreviation sometimes used in dictionaries).
'and' says to put letters next to each other.
'special' becomes 's' (common abbreviation as in Special Air Service).
'a'+'s'+'s'='ASS'
(Other definitions for ass that I've seen before include "Stupid person or American bum" , "jack" , "Moke" , "Pompous fool or beast of burden" , "Jennet" .)