In toilet, finally unwrap contraceptive (4)
I believe the answer is:
loop
'contraceptive' is the definition.
(type of intrauterine device)
'in toilet finally unwrap' is the wordplay.
'in' indicates putting letters inside.
'toilet' becomes 'lop' (I can't justify this - if you can you should believe this answer much more).
'finally' becomes 'last of all'.
'unwrap' means to look at the middle letters (I've seen 'unwrapping' mean this (letters which 'wrap' the word are removed)).
The middle letter of 'lastofall' is 'o'.
'lop' enclosing 'o' is 'LOOP'.
Can you help me to learn more?
(Other definitions for loop that I've seen before include "the knowledgeable are in it" , "Bight" , "Computer subroutine" , "Branch line" , "Contraception device - hearing aid" .)