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' is an insertion indicator.
'hat' becomes 'cap' (cap is a type of hat).
'm' placed within '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" .)