Photo data father altered without hesitation! (2,3,4,2,1,3)
I believe the answer is:
at the drop of a hat
'without hesitation' is the definition.
(I've seen this in another clue)
'photo data father altered' is the wordplay.
'altered' is an anagram indicator.
'photo'+'data'+'father'='photodatafather'
'photodatafather' is an anagram of 'AT THE DROP OF A HAT'.
(Other definitions for at the drop of a hat that I've seen before include "Derby's relegation signalled thus" , "just like that" , "When pork pie downed" , "without good reason?" , "Immediately" .)