Basic requirement of an office machine (6)
I believe the answer is:
staple
'basic' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for staple that I've seen before include "essential" , "Fastening device" , "key" , "Main, important" , "Main - way to fasten paper" .)