Main item of office equipment (6)
I believe the answer is:
staple
This clue might be a double definition.
'main' is the first definition.
(thesaurus)
'item of office equipment' is the second definition.
'staple' can be an answer for 'item' (thesaurus). I'm unsure of the 'of office equipment' bit.
Can you help me to learn more?
(Other definitions for staple that I've seen before include "(Of food) necessary and important" , "Important; paper fastener" , "Paper fastener - basic foodstuff" , "Raw material" , "A wire paper fastener for plates" .)