Row involves stray dog (7)
I believe the answer is:
terrier
'dog' is the definition.
(terrier is a kind of dog)
'row involves stray' is the wordplay.
'row' becomes 'tier' (a tier is a row of things).
'involves' indicates putting letters inside.
'stray' becomes 'err' (synonyms).
'tier' going around 'err' is 'TERRIER'.
(Other definitions for terrier that I've seen before include "One who volunteers to fight" , "Part-time soldier" , "Dog - army volunteer - land register" , "(Yorkshire?) dog" , "Small hunting dog" .)