A hitch not mentioned (4)
I believe the answer is:
knot
'a hitch' 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?
'not mentioned' is the wordplay.
'mentioned' shows a homophone (sound like).
'not' is a homophone of 'KNOT'.
Can you help me to learn more?
(Other definitions for knot that I've seen before include "Small northern sandpiper" , "Difficulty" , "Bird; tie securely" , "Could be a granny or a sheepshank" , "Reef or granny, say" .)