US leader in power, living (9)
I believe the answer is:
president
'us leader' is the definition.
(I've seen this before)
'power living' is the wordplay.
'power' becomes 'p'.
'living' becomes 'resident'.
'p'+'resident'='PRESIDENT'
'in' is the link.
(Other definitions for president that I've seen before include "Head of state of a republic" , "the boss" , "Head of US company - tried pens (anag)" , "such as Bush" , "Our head of state has a strange red instep" .)