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' (man's name. I am not sure about the 'with' bit.).
'spats' becomes 'tiffs' ('tiff' can be a synonym of 'spat').
'sam' in reverse letter order is '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?" .)