Pictures half back clinching silver (6)
I believe the answer is:
images
'pictures' is the definition.
('image' can be a synonym of 'picture')
'half back clinching silver' is the wordplay.
'half' becomes 'semi' (I've seen this before).
'back' says the letters should be written in reverse.
'clinching' is an insertion indicator.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'semi' back-to-front is 'imes'.
'imes' enclosing 'ag' is 'IMAGES'.
(Other definitions for images that I've seen before include "Likenesses, representations" , "Photos or representations" , "Semblances" , "Representations or reflections" , "Likenesses or mental pictures" .)