Deer - it's one with foot raised (6)
I believe the answer is:
wapiti
'deer' is the definition.
(wapiti is a kind of deer)
'it's one with foot raised' is the wordplay.
'one' becomes 'i' (Roman numeral).
'with' means one lot of letters go next to another.
'foot' becomes 'paw' (paw is a kind of foot**).
'raised' is a reversal indicator.
'paw' written backwards gives 'wap'.
'it'+'i'='iti'
'iti' after 'wap' is 'WAPITI'.
(Other definitions for wapiti that I've seen before include "Red deer - I paw it (anag)" , "I paw it (anag) - large North American deer" , "North American native" , "Deer with much-branched antlers" , "Animal" .)