About to have nothing but deer (3)
I believe the answer is:
roe
'deer' is the definition.
(I've seen this before)
'about to have nothing' is the wordplay.
'about' becomes 're' (regarding**).
'to have' is an insertion indicator.
'nothing' becomes 'o' (looks like zero - 0).
're' enclosing '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" .)