Strike starts to seriously limit actual production (4)
I believe the answer is:
slap
'strike' is the definition.
(slapping is a kind of striking)
'starts to seriously limit actual production' is the wordplay.
'starts to' indicates taking the first letters.
The initial letters of 'seriously limit actual production' is 'SLAP'.
(Other definitions for slap that I've seen before include "Strike (in the face)" , "Strike with the palm" , "Cuff" , "Strike action" , "Blow with open hand" .)