expression
new arrival; just arrived
Used as a noun or noun-modifying expression for someone or something that has just arrived. Often appears in phrases like 来立ての客 or 来立ての品.
来立ての客に部屋を案内した。
I showed the room to the guest who had just arrived.
来立ての荷物をまだ開けていない。
I haven't opened the package that just arrived yet.
着いたばかり is a more common and neutral way to say 'just arrived', while 来立て is a somewhat more literary or set expression.
Compound of 来 (ki, continuative form of 来る 'to come') + 立て (tate, suffix meaning 'just done'). The suffix 立て attaches to the continuative form of verbs to indicate that the action has just been completed.