The definition is Fresh investment in Arsenal, where "Arsenal" is a clever misdirection towards the football club — it actually refers to a stock of weapons, and rearmament means investing afresh in arms. The wordplay builds the answer in three parts: "on" gives RE, "wing" gives ARM, and "meant" is rearranged (indicated by "changes") to give AMENT. The phrase "at kick-off" hints at the ordering of these components from the start, giving RE + ARM + AMENT = REARMAMENT.