Craft makes one second turn round port (7)
I believe the answer is:
origami
'port' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'craft makes one second turn round' is the wordplay.
'craft makes' becomes 'riga' (I can't explain this - if you can you should believe this answer much more).
'one' becomes 'i' (Roman numeral).
'second' becomes 'mo' (both are short periods of time).
'turn' is a reversal indicator.
'round' indicates putting letters inside.
'i'+'mo'='imo'
'imo' back-to-front is 'omi'.
'riga' placed within 'omi' is 'ORIGAMI'.
Can you help me to learn more?
(Other definitions for origami that I've seen before include "work from folder" , "It's crafty folding" , "Jap. paper-folding art" , "The folding of sheets" , "Japanese craft of paper-tearing" .)