Free lunch a figment, ultimately fabricated (7)
I believe the answer is:
unlatch
'free' is the definition.
(thesaurus)
'lunch a figment ultimately fabricated' is the wordplay.
'ultimately' indicates one should take the final letters.
'fabricated' is an anagram indicator.
The last letter of 'figment' is 't'.
'lunch'+'a'+'t'='lunchat'
'lunchat' with letters rearranged gives 'UNLATCH'.
(Other definitions for unlatch that I've seen before include "Unfasten (a door)" , "Free bar" .)