Margaret turning up in strange petticoat (3)
I believe the answer is:
peg
'margaret' is the definition.
'turning up in strange petticoat' is the wordplay.
'turning up' says the letters should be written backwards.
'in' indicates a hidden word.
'gep' is hidden within 'strange petticoat'.
'gep' backwards is 'PEG'.
(Other definitions for peg that I've seen before include "Wooden pin, small marker" , "Kind of pin for hanging clothes" , "Brandy and soda drink measure" , "This leg is artificial" , "Clothes line fastener" .)