Shocked at first, actors get heated after several takes (6)
I believe the answer is:
aghast
'shocked' is the definition.
(synonyms)
'first actors get heated after several takes' is the wordplay.
'first' suggests taking the first letters.
The initial letters of 'actors get heated after several takes' is 'AGHAST'.
'at' acts as a link.
(Other definitions for aghast that I've seen before include "Filled with fear and consternation" , "Amazed" , "Deeply shocked" , "Very unhappy" , "Struck with horror" .)