Harsh call from Conservative about going for week on vacation (6)
I believe the answer is:
squawk
'harsh call' is the definition.
(a squawk is a harsh cry or call)
'conservative about going for week on vacation' is the wordplay.
I cannot really see how this works, but
'about' could be 'a' (abbreviation in Chambers) and 'a' is found in the answer.
'week' could be 'wk' (common abbreviation) and 'wk' is found within the answer.
This explanation may well be incorrect...
'from' acts as a link.
(Other definitions for squawk that I've seen before include "Bird's harsh noise" , "Loud harsh bird cry" , "Bird's harsh cry" , "Parrot's call" , "Croaky cry" .)