Think the son is staggering through drink (8)
I believe the answer is:
consider
'think' is the definition.
(I know that think can be written as consider)
'son is staggering through drink' is the wordplay.
'is staggering' indicates an anagram (letters stagger around).
'through' indicates putting letters inside (inserted letters go through the word).
'drink' becomes 'cider' (cider is a kind of drink).
'son' is an anagram of 'ons'.
'ons' put inside 'cider' is 'CONSIDER'.
'the' acts as a link.
(Other definitions for consider that I've seen before include "Deliberate" , "Think about, reflect upon" , "Go over something in one's mind" , "Take into account" , "Deem to be, believe" .)