Mount photo on card with details beginning to appear (3)
I believe the answer is:
ida
'mount' is the definition.
(Mount Ida is a mountain on Crete)
'photo on card with details beginning to appear' is the wordplay.
'photo on card with details' becomes 'ID' (identification card).
'beginning to' says to take the initial letters.
The initial letter of 'appear' is 'a'.
'id'+'a'='IDA'
(Other definitions for ida that I've seen before include "Princess __ (G&S comic opera)" , "Cretan mount" , "Name of girl or mountain" , "Cretan mountain - Gilbert and Sullivan princess" , "Classic mount" .)