Theatrical maiden wearing hat (4)
I believe the answer is:
camp
'theatrical' is the definition.
(I've seen this before)
'maiden wearing hat' is the wordplay.
'maiden' becomes 'm' (cricket abbreviation).
'wearing' means one lot of letters goes inside another.
'hat' becomes 'cap' (cap is a type of hat).
'm' placed inside 'cap' is 'CAMP'.
(Other definitions for camp that I've seen before include "Exaggerated in style for humorous effect - in tent?" , "Tent site" , "Military installation < affected" , "Live in a tent" , "Affected; base for troops" .)