Copy of a cot (4)
I believe the answer is:
crib
I believe this is a double definition.
'copy' is the first definition.
(I've seen this before)
'a cot' is the second definition.
(I know that cot can be written as crib)
'of' is the link.
(Other definitions for crib that I've seen before include "Infant's bed" , "Student's aid; bed" , "Cot - cattle stall - copy during an exam" , "Manger; illegally copy" , "Copy someone else's work" .)