Wolves grew older when put in a box (8)
I believe the answer is:
packaged
'when put in a box' is the definition.
I can't tell whether this definition defines the answer.
'wolves grew older' is the wordplay.
'wolves' becomes 'pack' (I can't justify this - if you can you should believe this answer much more).
'grew older' becomes 'aged' ('age' can be a synonym of 'grow older').
'pack'+'aged'='PACKAGED'
Can you help me to learn more?
(Other definitions for packaged that I've seen before include "kept under wraps?" , "ready for post? - with 26d" , "Placed in container" .)