Some explore, leisurely, a fabulous Rhine feature (7)
I believe the answer is:
lorelei
'fabulous rhine feature' is the definition.
(rock on the River Rhine Germany)
'some explore leisurely a' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'LORELEI' is hidden in the letters of 'explore leisurely a'.
(Other definitions for lorelei that I've seen before include "Legendary siren luring Rhine boatmen to destruction" , "Dangerous female" , "Great Rock on the Rhine where 37 across lived" , "Twenty down siren nymph; lie role (anag.)" , "Legendary German rock singer" .)