Images in solid form (5)
I believe the answer is:
idols
'images' is the definition.
(I know this)
'solid form' is the wordplay.
'form' is an anagram indicator (another form of the letters).
'solid' is an anagram of 'IDOLS'.
'in' acts as a link.
(Other definitions for idols that I've seen before include "Effigies worshipped as gods" , "Graven images sometimes worshipped" , "Much-admired persons" , "Heroes" , "Solid kind of images" .)