A trimming of lace one gathers (5)
I believe the answer is:
ruche
This clue could be a double definition.
'a trimming' is the first definition.
Both the definition and answer are singular nouns.
Maybe you can see a link between them that I can't see?
'lace one gathers' is the second definition.
The definition suggests a singular noun which matches the answer.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for ruche that I've seen before include "frilly lace" , "lacy frill" , "Pleated gathering of fabric" , "Frilled cloth as neck decoration" , "Pleated frilling" .)