Useful gift for doctor having fish in county estate, we’re told (7,6)
I believe the answer is:
bedside manner
'useful gift for doctor' is the definition.
(a doctor's manner with patients)
'fish in county estate we're told' is the wordplay.
'fish in county' becomes 'bedside' (I can't justify this - if you can you should give a lot more credence to this answer).
'estate' becomes 'manor' (manor is a kind of estate).
'we're told' indicates a 'sounds like' (homophone) clue.
'manor' sounds like 'manner'.
'bedside'+'manner'='BEDSIDE MANNER'
'having' acts as a link.
(Other definitions for bedside manner that I've seen before include "Doctor's people skills?" , "Doctor's approach or attitude to a patient" , "Doctor's demeanour with patient" , "Doctor's personal quality?" , "9 bearing" .)