Urge husband to drink up (4)
I believe the answer is:
push
'urge' is the definition.
(I've seen this before)
'husband to drink up' is the wordplay.
'husband' becomes 'h'.
'to drink' becomes 'sup' (I've seen this before**).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'h'+'sup'='hsup'
'hsup' reversed gives 'PUSH'.
(Other definitions for push that I've seen before include "Promote - drive" , "Energy" , "Propel forwards" , "Illegally supply" , "Promote (commodity)" .)