Modifying word (6)
I believe the answer is:
adverb
'modifying word' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for adverb that I've seen before include "Word such as 'madly'" , "Word that modifies another" , "Word as well, badly (gram.)" , "Word that qualifies another" , "Verb modifier" .)