South American writer regularly sets up tension (8)
I believe the answer is:
suspense
'tension' is the definition.
(thesaurus)
'south american writer regularly sets up' is the wordplay.
'south american' becomes 'sus' (I've seen this in other clues).
'writer' becomes 'pen' (I've seen this before**).
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'up' is a reversal indicator (in down clue: letters go upwards).
The alternate letters of 'sets' are 'es'.
'es' in reverse letter order is 'se'.
'sus'+'pen'+'se'='SUSPENSE'
(Other definitions for suspense that I've seen before include "Tense uncertainty" , "Pre-climactic excitement" , "Tense expectation" , "Discontinuance - indecision - excitement" , "Nervous anticipation" .)