See increases in slow slender creatures (7)
I believe the answer is:
lorises
'slow slender creatures' is the definition.
I know nothing about this answer so I can't judge whether this works.
'see increases' is the wordplay.
'see' becomes 'lo' (archaic exclamation meaning 'look!').
'increases' becomes 'rises' (rise is a kind of increase).
'lo'+'rises'='LORISES'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for lorises that I've seen before include "Primates" , "Mammals" .)