Ireland and US: works in progress (5,4)
I believe the answer is:
under sail
'progress' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'ireland and us works' is the wordplay.
'and' means one lot of letters go next to another.
'works' indicates an anagram (letters worked into a new form).
'ireland' put after 'us' is 'usireland'.
'usireland' is an anagram of 'UNDER SAIL'.
'in' is the link.
Can you help me to learn more?
(Other definitions for under sail that I've seen before include "(Of ship) with canvas up" , "prepared for a voyage" , "In a yacht" , "Where the deck is" , "Using wind power" .)