Reflected on hard image in code (6)
I believe the answer is:
cipher
'code' is the definition.
('cipher' can be a synonym of 'code')
'reflected on hard image' is the wordplay.
'reflected' says the letters should be written backwards.
'on' becomes 're' ('on' can be mean 'with reference to'**).
'hard' becomes 'h'.
'image' becomes 'pic' (I've seen this before).
're'+'h'+'pic'='rehpic'
'rehpic' written backwards gives 'CIPHER'.
'in' is the link.
(Other definitions for cipher that I've seen before include "Person or thing of no importance, or the symbol 0" , "A message written in code" , "Secret code" , "nobody" , "Nonentity" .)