Pass drink with son in middle of week (6)
I believe the answer is:
elapse
'pass' is the definition.
(I've seen this before)
'drink with son in middle of week' is the wordplay.
'drink' becomes 'lap' (lapping is a kind of drinking**).
'with' means one lot of letters go next to another.
'son' becomes 's'.
'in' indicates putting letters inside.
'middle of' indicates the central letters.
The middle letters of 'week' are 'ee'.
'lap'+'s'='laps'
'laps' inserted inside 'ee' is 'ELAPSE'.
(Other definitions for elapse that I've seen before include "pass in silence" , "Please (anag) -- pass away" , "Go by - pass away" , "Passing" , "Of time, pass by - please" .)