Reason for ship’s journal by international captain (5)
I believe the answer is:
logic
'reason' is the definition.
(logic is using reason)
'ship's journal by international captain' is the wordplay.
'ship's journal' becomes 'log' (I've seen this in another clue).
'by' means one lot of letters go next to another.
'international captain' becomes 'ic' (this could be a standard abbreviation I've not previously seen).
'log'+'ic'='LOGIC'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for logic that I've seen before include "Dialectics" , "The science of reasoning correctly" , "Sound sense" , "Branch of philosophy that analyses inference" , "Good reason" .)