Horse with wind knocked over old duke’s pompadour? (6)
I believe the answer is:
hairdo
'pompadour?' is the definition.
(pompadour is a kind of hairdo)
'horse with wind knocked over old duke's' is the wordplay.
'horse with' becomes 'h' (synonyms. I am not sure about the 'with' bit.).
'wind' becomes 'air' (air is a kind of wind).
'knocked over' is a reversal indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'duke' becomes 'd' (abbreviation).
'o'+'d'='od'
'od' backwards is 'do'.
'h'+'air'+'do'='HAIRDO'
(Other definitions for hairdo that I've seen before include "Possibly cut" , "Possibly a DA" , "Say, crew cut" , "Eg, beehive or mullet" , "The process of styling hirsute head" .)