Roguish Austen hero undressed Elizabeth finally (4)
I believe the answer is:
arch
'roguish' is the definition.
(I've seen this before)
'austen hero undressed elizabeth finally' is the wordplay.
'austen hero' becomes 'd'arcy' (I've seen this in another clue).
'undressed' means to look at the middle letters (the word removes the letters which clothe it).
'finally' indicates one should take the final letters.
The middle letters of 'darcy' are 'arc'.
The final letter of 'elizabeth' is 'h'.
'arc'+'h'='ARCH'
(Other definitions for arch that I've seen before include "Mysterious - curve" , "Roguish - chief - supporter" , "Vault; roguish" , "Curved bony structure in the foot" , "Devilish" .)