Noisy disagreement heard in fifth farm building? (6)
I believe the answer is:
barney
'noisy disagreement' is the definition.
(barney can informally mean an argument)
'heard in fifth farm building?' is the wordplay.
I cannot really see how this works, but
'building?' could be 'barn' (barn is a kind of building) and 'barn' is found within the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for barney that I've seen before include "Noisy quarrel (informal)" , "Dust-up" .)