It's taken to be abstemious (6)
I believe the answer is:
pledge
'be abstemious' is the definition.
I can't tell whether this defines the answer.
'it's taken' is the wordplay.
I cannot quite understand how this works, but
'taken' could be 'led' (to lead someone somewhere is to take them there) and 'led' is found within the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
This explanation may well be incorrect...
'to' acts as a link.
Can you help me to learn more?
(Other definitions for pledge that I've seen before include "Promise - security" , "Vow, affirm" , "make toast" , "Plight" , "assurance" .)