Action taken to reverse temper tantrums (4)
I believe the answer is:
step
'action taken' is the definition.
'reverse temper tantrums' is the wordplay.
'reverse' is a reversal indicator.
'temper tantrums' becomes 'pets' (old-fashioned UK term).
'pets' in reverse letter order is 'STEP'.
'to' is the link.
(Other definitions for step that I've seen before include "Indian garment" , "Second half of quick 20?" , "Abrupt change; pace" , "Bit of mashed potato maybe" , "Rung, dance movement" .)