Life peer holding sword (4)
I believe the answer is:
epee
'sword' is the definition.
(sword used in fencing)
'life peer holding' is the wordplay.
'holding' indicates a hidden word.
'EPEE' is hidden within 'life peer'.
(Other definitions for epee that I've seen before include "there's a point to it" , "Fencer's weapon" , "It may offer riposte" , "Fencing sword, heavier than a foil" , "Duelling weapon" .)