Delete witticism after former lover, for example, gets upset (7)
I believe the answer is:
expunge
'delete' is the definition.
(I know that expunge is a more specific form of the action delete)
'witticism after former lover for example gets upset' is the wordplay.
'witticism' becomes 'pun' (pun is a kind of witticism).
'after' says to put letters next to each other.
'former lover' becomes 'ex' (an ex-lover).
'for example' becomes 'e.g.' (short for 'exempli gratia', 'for example' in Latin).
'gets upset' says the letters should be written in reverse (I've seen 'getting upset' mean this).
'eg' reversed gives 'ge'.
'pun' put after 'ex' is 'expun'.
'expun'+'ge'='EXPUNGE'
(Other definitions for expunge that I've seen before include "Delete from the record" , "Cut it out!" , "Annihilate" , "Remove (from records)" , "Completely obliterate" .)