Some lass in Glencoe, unmarried (6)
I believe the answer is:
single
'unmarried' is the definition.
(similar in meaning)
'some lass in glencoe' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'SINGLE' is hidden within 'lass in glencoe'.
(Other definitions for single that I've seen before include "Unattached" , "Not in a relationship" , "Individual - unmarried" , "Free" , "Only one; record" .)