Fix some mousetraps (3)
I believe the answer is:
set
'fix' is the definition.
(I know that fix is a more specific form of set)
'some mousetraps' is the wordplay.
'some' indicates a hidden word (some parts of the word are used).
'SET' can be found hidden inside 'mousetraps'.
(Other definitions for set that I've seen before include "become firm" , "Group of things of the same kind that belong together" , "Badger's burrow" , "Cake < , plonk < , something served" , "Group; hard" .)