Tired-looking ship's company secures a mooring, periodically (8)
I believe the answer is:
careworn
'tired' is the definition.
(similar in meaning)
'company secures a mooring periodically' is the wordplay.
'company' becomes 'crew' (a group of people).
'secures' means one lot of letters goes inside another.
'periodically' indicates alternate letters (letters must be selected 'every so often').
The alternate letters of 'mooring' are 'orn'.
'crew' placed around 'a' is 'carew'.
'carew'+'orn'='CAREWORN'
'looking ship's' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for careworn that I've seen before include "Showing signs of stress and worry" , "Haggard, drawn" , "worn-out" , "Tired through worry" , "Run down by anxiety" .)