Mean, fit dogs hail from Rome (7)
I believe the answer is:
average
'mean' is the definition.
(I know that mean can be written as average)
'fit dogs hail from rome' is the wordplay.
I cannot really see how this works, but
'fit' could be 'rage' (I have seen 'Fit of anger ' mean 'rage' so perhaps 'fit' could also mean 'rage') and 'rage' is found within the answer.
'hail' could be 'ave' (greeting in Latin) and 'ave' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for average that I've seen before include "Usual - mediocre - mean" , "Arithmetically ordinary?" , "About normal or usual" , "building society customer loses capital over time" , "Mean - ordinary" .)