Poor houses left unlocked? (4)
I believe the answer is:
bald
'unlocked?' is the definition.
(having no locks of hair)
'poor houses left' is the wordplay.
'poor' becomes 'bad' (similar in meaning).
'houses' is an insertion indicator.
'left' becomes 'l' (common abbreviation).
'bad' going around 'l' is 'BALD'.
(Other definitions for bald that I've seen before include "Lacking hair on the scalp" , "Unadorned" , "Not covered with hair" , "Without hair" , "Lacking hair on the head" .)