Sword Conservative peer holds (4)
I believe the answer is:
epee
'sword' is the definition.
(sword used in fencing)
'conservative peer holds' is the wordplay.
'holds' indicates the answer is hidden within the clue.
'EPEE' is hidden within 'conservative peer'.
(Other definitions for epee that I've seen before include "Fencing sword similar to a foil" , "Foil for riposte" , "Fencing blade" , "Fencer's weapon" , "Duelling blade" .)