Sign with a hand that’s repulsed reviewer (9)
I believe the answer is:
'sign' is the definition.
(type of symbol)
'with a hand that's repulsed reviewer' is the wordplay.
'with' means one lot of letters go next to another.
'a hand' becomes 'aid' (giving someone a hand is helping or aiding them).
'that's repulsed' says the letters should be written backwards.
'reviewer' becomes 'critic' (I've seen this before).
'aid' backwards is 'dia'.
'dia' put next to 'critic' is 'DIACRITIC'.
(Other definitions for diacritic that I've seen before include "grave perhaps" , "accent, for example" , "one showing a pronounced difference" , "Mark" , "[ACCENT] , perhaps" .)