Certain to tuck into boozy drink? Steady! (8)
I believe the answer is:
measured
'steady' is the definition.
(thesaurus)
'certain to tuck into boozy drink?' is the wordplay.
'certain' becomes 'sure' (similar in meaning).
'to tuck into' is an insertion indicator.
'boozy drink?' becomes 'mead' (mead is a kind of drink. I am not sure about the 'boozy' bit.).
'sure' put inside 'mead' is 'MEASURED'.
Can you help me to learn more?
(Other definitions for measured that I've seen before include "Made sure (anag.)" , "certain content of alcohol" , "Determined the dimensions" , "Evaluated" , "Regular in movement or carefully considered" .)