By five one's in, cooking the meat (7)
I believe the answer is:
venison
'meat' is the definition.
(I know that venison is a game meat)
'by five one's in cooking' is the wordplay.
'by' is a charade indicator (letters next to each other).
'five' becomes 'V' (Roman numeral).
'cooking' indicates an anagram (cook can mean to falsify or distort).
'ones'+'in'='onesin'
'onesin' with letters rearranged gives 'enison'.
'v' put next to 'enison' is 'VENISON'.
'the' is the link.
(Other definitions for venison that I've seen before include "Meat - in ovens (anag)" , "Deer meat" , "Type of meat" , "Flesh of deer" , "Game" .)