Distant waves and cheers when minister’s house opens (6,3)
I believe the answer is:
tasman sea
'distant waves' is the definition.
(sea in the southern hemisphere)
'cheers when minister's house opens' is the wordplay.
'cheers' becomes 'ta' (both can informally mean thank you).
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'minister's house' becomes 'manse' (house assigned to a religious minister).
'opens' is an insertion indicator (one set of letters makes an 'opening' in another).
'as'+'manse'='asmanse'
'ta' placed around 'asmanse' is 'TASMAN SEA'.
'and' acts as a link.
(Other definitions for tasman sea that I've seen before include "Ocean area between Australia and New Zealand" , "Cook explored here" , "Body of water separating Australia and New Zealand" , "an arm of the Pacific" , "The main" .)