Pile of exposed photographs? (3)
I believe the answer is:
nap
'pile' is the definition.
(I've seen this before)
'exposed photographs?' is the wordplay.
'exposed' means to look at the middle letters (outside letters removed).
'photographs?' becomes 'snaps' ('snap' can be a synonym of 'photograph').
The central letters of 'snaps' are 'NAP'.
'of' acts as a link.
(Other definitions for nap that I've seen before include "Sleep - card game - fibres on a snooker table" , "Raised surface of a fabric and short sleep" , "A short sleep or snooze" , "A brief snooze" , "Sleep lightly" .)