Page with greeting in letter from abroad (3)
I believe the answer is:
phi
'letter from abroad' is the definition.
(letter of the Greek alphabet)
'page with greeting' is the wordplay.
'page' becomes 'p'.
'with' is a charade indicator (letters next to each other).
'greeting' becomes 'hi' (hi is a kind of greeting).
'p'+'hi'='PHI'
'in' is the link.
(Other definitions for phi that I've seen before include "One Greek" , "21st Greek letter" , "Greek letter; hip (anag.)" , "Greek character" , "letter to Timon?" .)