Postpone work on missile attached to plane (8)
I believe the answer is:
Here is my best explanation:
'postpone work' is the definition.
(I've seen this before)
'missile attached to plane' is the subsidiary indication.
'missile' becomes 'ball' (ball is a kind of missile).
'attached to' is a charade indicator (letters next to each other).
'plane' becomes 'moth' (Tiger Moth is an example).
'ball' after 'moth' is 'mothball'.
'on' is the link.
(Other definitions for mothball that I've seen before include "Put on ice", "Insect repellent", "Lay aside indefinitely", "put on back burner", "Postpone work", "Small sphere to keep insects from eating clothes", "Camphor sphere used to keep stored clothing in good condition", "Put into long-term storage", "Naphthalene or camphor sphere" and "Sphere of camphor".)