Word from initials (7)
I believe the answer is:
acronym
'word from initials' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for acronym that I've seen before include "NATO's one" , "Word made up of initials" , "Mar cony (anag)" , "Word made from initial letters of other words" , "Ernie, perhaps" .)