Fit well together (4)
I believe the answer is:
mesh
'fit well together' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for mesh that I've seen before include "Net fabric" , "Become entangled - become engaged" , "Web" , "Knit or weave for Shem" , "Undeviating" .)