It's little more than a foot long (4)
I believe the answer is:
shoe
'long' is the definition.
Although both the answer and definition are verbs in their base form, I cannot understand how they can define each other.
'it's little more than a foot' is the wordplay.
'it's' becomes 'e's' ('e' can mean 'electronic' which is similar to 'IT').
'little' means to remove the last letter (the word is not quite complete).
'more than' is a charade indicator (letters next to each other).
'a foot' becomes 'sho' (I can't justify this - if you can you should believe this answer much more).
'es' with its last letter taken away is 'e'.
'e' put after 'sho' is 'SHOE'.
Can you help me to learn more?
(Other definitions for shoe that I've seen before include "something afoot" , "Camera mounting" , "Loafer, say" , "Eg, brogue" , "Oxford, say" .)