Dagger bound in the end to irritate (4)
I believe the answer is:
dirk
'dagger' is the definition.
(dirk is a kind of dagger)
'bound in the end to irritate' is the wordplay.
'in the end' suggests the final letters.
'to irritate' becomes 'irk' (I've seen this before**).
The final letter of 'bound' is 'd'.
'd'+'irk'='DIRK'
(Other definitions for dirk that I've seen before include "weapon" , "A short Scottish dagger" , "Highland dagger" , "Scottish Highlander's dagger" , "Daggert" .)