Smile coyly (6)
I believe the answer is:
simper
'smile coyly' is the definition.
(to simper is to smile in an exaggeratedly coy way)
This is all the clue.
(Other definitions for simper that I've seen before include "Primes to smile in affected way" , "Primes to laugh affectedly" , "Smile in a silly way" , "Smile coyly" , "Smirk" .)