Time ship-worker joined cause (7)
I believe the answer is:
trigger
'cause' is the definition.
(I know that trigger is a more specific form of the action initiate)
'time ship-worker joined' is the wordplay.
I cannot really understand how this works, but
'time' could be 't' (abbreviation) and 't' is found within the answer.
'worker' could be 'rigger' (rigger is a kind of worker) and 'rigger' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for trigger that I've seen before include "Pull it to discharge gun" , "Gun release mechanism" , "Gun-firing device" , "Lever on gun" , "Part of gun" .)