Wandering Chinese leader is back in band (7)
I believe the answer is:
roaming
'wandering' is the definition.
('roam' can be a synonym of 'wander')
'chinese leader is back in band' is the wordplay.
'chinese leader' becomes 'Mao' (Chairman Mao).
'is back' says the letters should be written in reverse.
'in' is an insertion indicator.
'band' becomes 'ring' (a ring is a band of metal).
'mao' in reverse letter order is 'oam'.
'oam' placed into 'ring' is 'ROAMING'.
(Other definitions for roaming that I've seen before include "wandering around" , "Roving" , "Ranging widely" , "Using a mobile on another network" , "Moving about" .)