Reach with thanks into a tin (6)
I believe the answer is:
attain
'reach' is the definition.
(I know that reach is a kind of attain)
'thanks into a tin' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'into' means one lot of letters goes inside another.
'a'+'tin'='atin'
'ta' going inside 'atin' is 'ATTAIN'.
'with' is the link.
(Other definitions for attain that I've seen before include "Reach (a particular age)" , "Bring off" , "Manage to get" , "Succeed in accomplishing; reach" , "Achieve with effort" .)