Careful, certainly, spiking sweet drink with alcohol (8)

I believe the answer is:
measured
'careful' is the definition.
(synonyms)
'certainly spiking sweet drink with alcohol' is the wordplay.
I cannot quite see how this works, but
'certainly' could be 'sure' (synonyms) and 'sure' is located in the answer.
'drink' could be 'mead' (mead is a kind of drink) and 'mead' is found in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for measured that I've seen before include "Carefully considered and restrained" , "Determine dimensions" , "Weighed" , "Gauged - regulated - steady" , "Regular in movement or carefully considered" .)
