English nobleman's short sword (4)
I believe the answer is:
epee
'sword' is the definition.
(epee is a kind of sword)
'english nobleman's short' is the wordplay.
'english' becomes 'e' (abbreviation).
'nobleman' becomes 'peer' (peer is a kind of nobleman).
'short' means to remove the last letter.
'peer' with its last letter taken away is 'pee'.
'e'+'pee'='EPEE'
(Other definitions for epee that I've seen before include "Narrow fencing sword" , "Fencer's sword" , "sports equipment" , "It may offer riposte" , "there's a point to it" .)