Dogs upset man with spats (8)
I believe the answer is:
mastiffs
'dogs' is the definition.
(mastiff is a kind of dog)
'upset man with spats' is the wordplay.
'upset' says the letters should be written backwards.
'man with' becomes 'sam' (I am not sure about the 'with' bit.).
'spats' becomes 'tiffs' ('tiff' can be a synonym of 'spat').
'sam' written backwards gives 'mas'.
'mas'+'tiffs'='MASTIFFS'
Can you help me to learn more?
(Other definitions for mastiffs that I've seen before include "Powerful deep-chested dogs" , "man's best friends?" .)