Space to move (6)
'space to move' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for elbowroom that I've seen before include "Space to function" , "Bowl Romeo out to get some space" , "Enough space to work or move in - flex arm" , "Enough scope to function" , "Leeway" .)
(Other definitions for leeway that I've seen before include "Amount of freedom" , "Elbowroom" , "Allowance" , "Margin, latitude, room" , "Slack" .)