Greek character’s back to front in photo - sorry! (8)
I believe the answer is:
pathetic
'sorry' is the definition.
(thesaurus)
'greek character's back to front in photo' is the wordplay.
'greek character's back' becomes 'athe' (I am not sure about this - if you are sure you should believe this answer much more).
'front' suggests taking the first letters.
'in' is an insertion indicator.
'photo' becomes 'pic' (I've seen this before).
The initial letter of 'to' is 't'.
'athe'+'t'='athet'
'athet' going within 'pic' is 'PATHETIC'.
(Other definitions for pathetic that I've seen before include "Feeble; inspiring pity" , "Contemptible" , "Poor" , "arousing contempt" , "Pitiable, inadequate" .)