This is a container clue - one word or phrase goes inside (or around) another to form the answer.
Look for a word meaning 'one' that goes inside a phrase meaning 'for hire'. The phrase 'for hire' acts as the container, wrapping around the word for 'one'.
Answer: TOILET | 'One' = I, which goes inside 'for hire' = TO LET, giving TO(I)LET = TOILET (slang for John)