An impediment to massage (3)
I believe the answer is:
rub
I believe this clue is a double definition.
'an impediment' is the first definition.
(I know that rub is a type of obstacle)
'massage' is the second definition.
(rub can mean to massage)
'to' acts as a link.
(Other definitions for rub that I've seen before include "Central difficulty" , "Cause friction" , "Polish - difficulty" , "Remove marks - ... out" , "Abrade" .)