Oddly paranoid having lost a small dagger (7)
I believe the answer is:
poniard
'small dagger' is the definition.
(I've seen this in another clue)
'oddly paranoid having lost a' is the wordplay.
'oddly' indicates an anagram.
'having lost' is a deletion indicator.
'paranoid' with 'a' taken out is 'pranoid'.
'pranoid' anagrammed gives 'PONIARD'.
(Other definitions for poniard that I've seen before include "straight crease?" , "Slender dagger" , "A drop in (anag) - dagger" , "Thin knife" .)