Sisters embracing or king lost for words (5)
I believe the answer is:
nouns
'words' is the definition.
(noun is a kind of word)
'sisters embracing or king lost' is the wordplay.
'sisters' becomes 'nuns' (I've seen this before).
'embracing' is an insertion indicator.
'king' becomes 'R' (abbreviation of Latin rex).
'lost' suggests deleting specific letters.
'or' with 'r' taken away is 'o'.
'nuns' placed around 'o' is 'NOUNS'.
'for' acts as a link.
(Other definitions for nouns that I've seen before include "They refer to people, places and things" , "terms" , "Words used as names of places or things" , "Identifying words" , "Naming words" .)