One thing or a couple? (4)
I believe the answer is:
This clue is a double definition.
'one thing' is the first definition.
(an item is a thing)
'a couple' is the second definition.
(a romantic couple are 'an item')
(Other definitions for item that I've seen before include "Separate object or unit" , "A thing or unit" , "Seperate article in an enumeration" , "Unit; detail" , "Bit of information" .)