Public consuming a cold ham (7)
I believe the answer is:
overact
'ham' is the definition.
(ham can mean to overact)
'public consuming a cold' is the wordplay.
'public' becomes 'overt' (both can mean well-known or unconcealed).
'consuming' is an insertion indicator.
'cold' becomes 'C' (eg on taps).
'a'+'c'='ac'
'overt' going around 'ac' is 'OVERACT'.
(Other definitions for overact that I've seen before include "Don't expect Oscar" , "Play part exaggeratedly" , "Perform in an exaggerated manner" , "Play role exaggeratedly" , "Play (part) in an exaggerated manner" .)