Tool satisfied everyone inside (6)
I believe the answer is:
mallet
'tool' is the definition.
(mallet is a kind of tool)
'satisfied everyone inside' is the wordplay.
'satisfied' becomes 'met' ('meet' can be a synonym of 'satisfy').
'everyone' becomes 'all' (I've seen this before).
'inside' means one lot of letters goes inside another.
'met' enclosing 'all' is 'MALLET'.
(Other definitions for mallet that I've seen before include "An auctioneer's wooden hammer" , "It's used in croquet and polo" , "Used to beat" , "Wooden-headed hammer" , "Type of hammer" .)