Outskirts of Harare under rising river's surge (6)
I believe the answer is:
seethe
'surge' is the definition.
(I've seen this before)
'outskirts of harare under rising river's' is the wordplay.
'outskirts of' suggests removing the centre.
'under' means one lot of letters go next to another.
'rising' shows that the letters should be reversed in order (going up in a down clue).
'river' becomes 'tees' (River Tees).
'harare' with its middle removed is 'he'.
'tees' in reverse letter order is 'seet'.
'he' put after 'seet' is 'SEETHE'.
(Other definitions for seethe that I've seen before include "(Of liquid) move as if boiling" , "Boil; fume with suppressed rage" , "get very angry" , "Boil turbulently" , "get very agitated" .)