Irate six-footer fed with one pastry (9)
I believe the answer is:
croissant
'pastry' is the definition.
(I have seen 'French pastry ' mean 'croissant' so perhaps 'pastry' could also mean 'croissant')
'irate six-footer fed with one' is the wordplay.
'irate' becomes 'cross' (I've seen this before).
'six footer' becomes 'ant' (an ant has six feet).
'fed with' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'cross'+'ant'='crossant'
'crossant' enclosing 'i' is 'CROISSANT'.
(Other definitions for croissant that I've seen before include "food item" , "Tasty crescent-shaped French bread roll" , "that baker turns out" , "Breakfast item" , "French pastry" .)