Lack of physical exercise stops nude cast waiting to be revealed (8)
I believe the answer is:
unopened
'waiting to be revealed' is the definition.
I can't tell whether this definition defines the answer.
'lack of physical exercise stops nude cast' is the wordplay.
'lack of' becomes 'no' (lack of money is no money).
'physical exercise' becomes 'pe'.
'stops' is an insertion indicator (stopping can mean blocking a gap).
'cast' is an anagram indicator (letters are dispersed or cast around).
'no'+'pe'='nope'
'nude' anagrammed gives 'uned'.
'nope' placed within 'uned' is 'UNOPENED'.
Can you help me to learn more?
(Other definitions for unopened that I've seen before include "Having held onto seal" , "Still closed" , "Still sealed as post may be" , "Remaining sealed" , "shut" .)