Thinks they're sisters (5)
I believe the answer is:
muses
This might be a double definition.
'thinks' is the first definition.
(musing is a kind of thinking)
'sisters' is the second definition.
The definition and answer can be both people as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
'they're' acts as a link.
Can you help me to learn more?
(Other definitions for muses that I've seen before include "Meditates on the nine goddesses" , "Thinks" , "Clio, Euterpe, Terpsichore etc" , "In Greek and Roman myth, nine goddesses of the arts" , "Contemplates" .)