Rum or the small beer for partner (5,4)
I believe the answer is:
other half
'partner' is the definition.
(I've seen this before)
'rum or the small beer' is the wordplay.
'rum' indicates an anagram (rum can mean strange or unusual).
'small beer' becomes 'half'.
'or'+'the'='orthe'
'orthe' with letters rearranged gives 'other'.
'other'+'half'='OTHER HALF'
'for' acts as a link.
(Other definitions for other half that I've seen before include "partner" , "Wife or hubby" , "Spouse" , "people better off than us?" , "Dutch" .)