One in eight finished lease after month (8)
I believe the answer is:
octuplet
'one in eight' is the definition.
The definition suggests a singular noun which matches the answer.
'finished lease after month' is the wordplay.
'finished' becomes 'up' ('up' can be similar in meaning to 'finished').
'lease' becomes 'let' ('let' can be a synonym of 'lease').
'after' means one lot of letters go next to another.
'month' becomes 'oct' (Oct is an example**).
'up'+'let'='uplet'
'uplet' after 'oct' is 'OCTUPLET'.
Can you help me to learn more?
(Other definitions for octuplet that I've seen before include "One of a group of eight children born at the same time" , "One of eight born together" , "One of eight in birth" .)