Ship’s dog having short run (7)
I believe the answer is:
collier
'ship's' is the definition.
(I've seen this before)
'dog having short run' is the wordplay.
I cannot really see how this works, but
'dog' could be 'collie' (collie is a kind of dog) and 'collie' is present in the answer.
'run' could be 'r' (cricket abbreviation) and 'r' 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 collier that I've seen before include "unable to avoid contact with mine" , "Geordie Jack, commonly" , "Ship carrying coal" , "Painter" , "Pitman" .)