Smile (4)
'smile' is the definition.
(grinning is a kind of smiling)
This is all the clue.
(Other definitions for grin that I've seen before include "Wide smile" , "Accept with good grace - . . . . and bear it" , "Smile wryly" , "Ring (anag.)" , "A broad smile showing the teeth" .)
'smile' is the definition.
(smirking is a kind of smiling)
This is the entire clue.
(Other definitions for smirk that I've seen before include "Complacent smile" , "Silly smile" , "Leer" , "Show self-complacent satisfaction" , "Self-satisfied smile" .)