Dog in dispute involving old woman? (7)
I believe the answer is:
mastiff
'dog' is the definition.
(mastiff is a kind of dog)
'dispute involving old woman?' is the wordplay.
I cannot really understand how this works, but
'dispute' could be 'tiff' (tiff is a kind of dispute) and 'tiff' is found within the answer.
'old woman?' could be 'ma' (both can mean someone's mother) and 'ma' is found within the answer.
A single letter 's' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' acts as a link.
(Other definitions for mastiff that I've seen before include "Powerful dog breed" , "one of his best friends?" , "Hound" , "Big dog" , "Large, powerful, short-haired dog" .)