Top phonetic
能 supplies the sound — néng shifted to xióng through onset and rime drift, a long-distance change.
能 itself was originally a pictograph of a bear (the head
厶, body
月, and four legs
匕匕). When
能 was reborrowed for 'able, capable', a
火/
灬 radical was added below to preserve the original 'bear' meaning — yielding modern
熊.