Signs are in positions around eastern run (7)
I believe the answer is:
posters
'signs' is the definition.
(poster is a kind of sign)
'in positions around eastern run' is the wordplay.
'in' means one lot of letters goes inside another.
'positions' becomes 'posts' (post is a kind of position).
'around eastern run' becomes 'er' (I am not sure about this - if you are sure you should believe this answer much more).
'posts' enclosing 'er' is 'POSTERS'.
'are' acts as a link.
Can you help me to learn more?
(Other definitions for posters that I've seen before include "Contributors to forum" , "Public placards" , "Placards, notices" , "Bills or placards on walls" .)