Show still entertaining suits from the south (7)
I believe the answer is:
testify
'show' is the definition.
(I know that show can be written as testify)
'still entertaining suits from the south' is the wordplay.
'still' becomes 'yet' (yet can mean still or so far).
'entertaining' indicates putting letters inside (inviting in, as for dinner).
'suits' becomes 'fits' ('fit' can be a synonym of 'suit').
'from the south' says the letters should be written backwards (in a down clue, letters go up).
'yet' going around 'fits' is 'yfitset'.
'yfitset' written backwards gives 'TESTIFY'.
(Other definitions for testify that I've seen before include "Affirm (on oath)" , "take the stand" , "Bear witness in court" , "sworn" , "Give evidence in court" .)