Female to startle in a dress (5)
I believe the answer is:
frock
'a dress' is the definition.
('frock' can be a synonym of 'dress')
'female to startle' is the wordplay.
'female' becomes 'f' (abbreviation).
'to startle' becomes 'rock' (I've seen this before).
'f'+'rock'='FROCK'
'in' is the link.
(Other definitions for frock that I've seen before include "Party dress?" , "Long gown worn by priests; woman's dress" , "Demon" , "something to put on" .)