Put up flag over jetty and decking (10)

'decking' is the definition.
The answer and definition can be both to do with creating things as well as being present participle verbs.
Maybe there's a link between them I don't understand?

'put up flag over jetty' is the wordplay.
'put up' says the letters should be written in reverse.
'flag' becomes 'rag' (a flag might be a rag).
'over jetty' becomes 'landing' (I can't explain this - if you can you should believe this answer much more).
'rag' backwards is 'gar'.
'gar'+'landing'='GARLANDING'

'and' acts as a link.

Can you help me to learn more?