They hang from trees, and pack a change of kit in metal boxes (7)

(Source: London Evening Standard)

"a change of kit" ⇒ anagram of "kit" ⇒ e.g. "tki"

"metal boxes" ⇒ also "cans"

"tki" inside "cans"

Something that hangs from trees ⇒ possibly a leaf or a seed pod

"catkins"