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' shows that the letters should be reversed in order.
'in' means one lot of letters goes inside another.
'band' becomes 'ring' (a ring is a band of metal).
'mao' backwards is 'oam'.
'oam' going into '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" .)