In horticultural hands it has a disturbing effect (3)
I believe the answer is:
hoe
'in horticultural hands' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'it has a disturbing effect' is the wordplay.
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'has' says to put letters next to each other.
'a disturbing effect' becomes 'ho' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'e' put after 'ho' is 'HOE'.
Can you help me to learn more?
(Other definitions for hoe that I've seen before include "Weeding implement" , "gardening implement" , "Garden implement" , "Attend to beds" , "Tool for loosening soil and scraping up weeds" .)