Visiting centre of Brunei, see swamp (8)
I believe the answer is:
inundate
'swamp' is the definition.
(I know that swamp can be written as inundate)
'visiting centre of brunei see' is the wordplay.
'visiting' becomes 'in'.
'centre of' indicates the central letters.
'see' becomes 'date' (synonyms).
The middle of 'brunei' is 'un'.
'in'+'un'+'date'='INUNDATE'
(Other definitions for inundate that I've seen before include "Overwhelm (as if) with water" , "Flood, cover with water" , "'Flood, swamp (8)'" , "be overwhelming" , "Flood (a place)" .)