They can fit very nicely, back to front (6)
I believe the answer is:
spoons
'they' is the definition.
Both the definition and answer are plural nouns.
Perhaps they are linked in a way I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for spoons that I've seen before include "Runcible eating irons?" , "Percussion instrument" , "Table utensils as for soup" , "More than one server" , "Eating implements" .)