Some sidearms needed for scheme
I believe the answer is:
idea
'scheme' is the definition.
(I've seen this in another clue)
'some sidearms needed' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'IDEA' can be found hidden inside 'sidearms needed'.
'for' is the link.
(Other definitions for idea that I've seen before include "Purpose" , "It comes to mind" , "Proposal" , "Notion, concept" , "Thought; concept" .)