Crooned to girls in shades (10)
I believe the answer is:
sunglasses
'shades' is the definition.
(synonyms)
'crooned to girls' is the wordplay.
'crooned' becomes 'sung' (I've seen this in another clue).
'to girls' becomes 'lasses' (lass can mean a girl).
'sung'+'lasses'='SUNGLASSES'
'in' acts as a link.
(Other definitions for sunglasses that I've seen before include "assumed to protect pupils?" , "summer wear" , "viewing aids" , "They relieve effect of glaring" , "These offer a sight more protection" .)