One disparaging farm machinery (12)

'one disparaging' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'farm machinery' is the wordplay.
I cannot really see how this works, but
'farm' could be 'spread' (spread is a kind of farm) and 'spread' is present in the answer.
The remaining letters 'mucker' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?