A woman in flannel (4)
I believe the answer is:
anne
'a woman' is the definition.
(woman's name)
'in flannel' is the wordplay.
'in' says the answer is hidden in the clue.
'ANNE' is hidden in the letters of 'flannel'.
(Other definitions for anne that I've seen before include "Name of queen or princess" , "Queen seventeen hundred and two to seventeen fourteen" , "Henry's second" , "Queen's name" , "Queen 1702-1714" .)