City cleaner has one type of seat (4,5)
I believe the answer is:
bath chair
'type of seat' is the definition.
'city cleaner has one' is the wordplay.
'city' becomes 'bath' (I've seen this before**).
'cleaner' becomes 'char' (charwoman is a type of cleaner).
'has' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'char' placed around 'i' is 'chair'.
'bath'+'chair'='BATH CHAIR'
(Other definitions for bath chair that I've seen before include "post in SW university?" , "Invalid transport" , "Former invalid's carriage" , "Invalid carrier" , "Seat for invalid" .)