Unsmiling face of stranded flyer (5)
I believe the answer is:
stern
'unsmiling' is the definition.
(I've seen this before)
'face of stranded flyer' is the wordplay.
'face of' says to take the initial letters.
'flyer' becomes 'tern'.
The first letter of 'stranded' is 's'.
's'+'tern'='STERN'
(Other definitions for stern that I've seen before include "Grave; rear" , "Hard - back" , "Back end of a ship" , "Old star" , "Dour" .)