The man taking control of old American parliament (5)
I believe the answer is:
house
'parliament' is the definition.
(the House of Commons)
'the man taking control of old american' is the wordplay.
'the man' becomes 'he' (he refers to a man).
'taking control of' indicates putting letters inside.
'old' becomes 'o' (abbreviation).
'american' becomes 'US' (United States).
'o'+'us'='ous'
'he' enclosing 'ous' is 'HOUSE'.
(Other definitions for house that I've seen before include "Inn" , "SECOND PART OF 19" , "Residence, dwelling" , "Dwelling, living quarters (5)" , "Residence; legislative meeting-place" .)