Nomadic Chinese leader turns up in band (7)
I believe the answer is:
roaming
'nomadic' is the definition.
(thesaurus)
'chinese leader turns up in band' is the wordplay.
'chinese leader' becomes 'Mao' (Chairman Mao).
'turns up' says the letters should be written in reverse.
'in' means one lot of letters goes inside another.
'band' becomes 'ring' (a ring is a band of metal).
'mao' backwards is 'oam'.
'oam' placed within 'ring' is 'ROAMING'.
(Other definitions for roaming that I've seen before include "wandering around" , "Ranging widely" , "Using a mobile on another network" , "Roving" , "Moving about" .)