Life peer stores a fencing tool (4)
I believe the answer is:
epee
'a fencing tool' is the definition.
(I've seen this in another clue)
'life peer stores' is the wordplay.
'stores' indicates the answer is hidden within the clue.
'EPEE' is hidden in the letters of 'life peer'.
(Other definitions for epee that I've seen before include "Duelling blade" , "Fencer's weapon" , "sports equipment" , "Fighting blade" , "Sharp-pointed duelling sword" .)