Parts or pieces that fit with others (8)
I believe the answer is:
segments
'parts or pieces that fit with others' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for segments that I've seen before include "'Sections, pieces (8)'" , "Nets gems in separate parts" , "Parts or pieces that fit with others" , "Parts, pieces, portions" , "Portions or divisions, as of grapefruit" .)