Wide open space in centre of Bangkok (6)
I believe the answer is:
gaping
'wide open' is the definition.
(I've seen this before)
'space in centre of bangkok' is the wordplay.
'space' becomes 'gap' (gap is a kind of space**).
'centre of' says to take the centre.
The centre of 'bangkok' is 'g'.
'gap'+'in'+'g'='GAPING'
(Other definitions for gaping that I've seen before include "Opening mouth wide or staring in wonder" , "Staring open-mouthed" , "Yawning" , "With the mouth wide open, in wonder perhaps" .)