Large-scale part in adventure picture (4)
I believe the answer is:
epic
'large-scale' is the definition.
(I've seen this before)
'part in adventure picture' is the wordplay.
'part in' indicates a hidden word.
'EPIC' is hidden in the letters of 'adventure picture'.
(Other definitions for epic that I've seen before include "Exodus, say" , "Impressively great" , "of impressive proportions?" , "On a grand scale, maybe a poem" , "On a grand scale like long poem" .)