Part of Somerset he realised is heavenly (8)
I believe the answer is:
ethereal
'heavenly' is the definition.
(similar in meaning)
'part of somerset he realised' is the wordplay.
'part of' indicates a hidden word.
'ETHEREAL' is hidden in the letters of 'somerset he realised'.
'is' is the link.
(Other definitions for ethereal that I've seen before include "'Delicate, heavenly (8)'" , "Very delicate - tale here (anag)" , "Take ale there: it's light and delicate" , "Spiritual" , "Insubstantial or heavenly" .)