Breaking into shopping centre, both put away for a long time (8)
I believe the answer is:
mothball
'put away for a long time' is the definition.
(mothball can mean to put in storage)
'breaking into shopping centre both' is the wordplay.
I cannot quite see how this works, but
an anagram of 'both' is 'othb' which is present in the answer.
'shopping centre' could be 'mall' (a mall is a large shopping complex) and 'mall' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
(Other definitions for mothball that I've seen before include "Put under wraps" , "put on back burner" , "Postpone work" , "Insect repellent" , "Put on ice" .)