Girl in glasses (4)
I believe the answer is:
'girl' is the definition.
(lass can informally mean a girl)
'in glasses' is the wordplay.
'in' indicates the answer is hidden within the clue.
'LASS' can be found hidden inside 'glasses'.
(Other definitions for lass that I've seen before include "Sweetheart" , "Familiar form of address for female" , "Sweet resident of Richmond Hill?" , "Girl (of Richmond Hill?)" , "Damsel" .)