Tidy end of gammon devoured (6)
I believe the answer is:
neaten
'tidy' is the definition.
(I know that tidy can be written as neaten)
'end of gammon devoured' is the wordplay.
'end of' indicates one should take the final letters.
'devoured' becomes 'eaten' (similar in meaning).
The last letter of 'gammon' is 'n'.
'n'+'eaten'='NEATEN'
(Other definitions for neaten that I've seen before include "Make orderly" , "Straighten up" , "set in order" , "Make tidy" , "Spruce up" .)