Silver's hiding part of face in pain (6)
I believe the answer is:
aching
'in pain' is the definition.
(I've seen this before)
'silver's hiding part of face' is the wordplay.
'silver' becomes 'ag' (Ag is the chemical symbol for silver).
'hiding' is an insertion indicator.
'part of face' becomes 'chin' ('chin' is part of 'face').
'ag' going around 'chin' is 'ACHING'.
(Other definitions for aching that I've seen before include "Yearning; in pain" , "Painful" , "Feeling pain" , "Suffering a dull persistent pain" , "Sore" .)