About to have nothing but deer (3)
I believe the answer is:
roe
'deer' is the definition.
(roe deer is a kind of deer)
'about to have nothing' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'to have' indicates putting letters inside.
'nothing' becomes 'O' (looks like zero - 0).
're' placed around 'o' is 'ROE'.
'but' acts as a link.
(Other definitions for roe that I've seen before include "A mass of fish-eggs" , "eg Caviare" , "Fish eggs; small deer" , "Food from fish" , "Part of fish, sounds like go through water" .)