It's certainly not a distaff! (5)
I believe the answer is:
spear
'a distaff' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'it's certainly not' is the wordplay.
I cannot quite see how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
The remaining letters 'spar' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for spear that I've seen before include "Simple weapon" , "Stabbing, throwing, weapon" , "Pole with pointed end" , "Lance" , "Weapon to throw" .)