Red scarcely seen (4)
I believe the answer is:
rare
I believe this clue is a double definition.
'red' is the first definition.
(as in a rare steak)
'scarcely seen' is the second definition.
(something rare is seldom or scarcely seen)
(Other definitions for rare that I've seen before include "Scarcely seen" , "few and far between" , "Seldom encountered" , "Very scarce and probably valuable" , "Occurring infrequently" .)