Leap year. Perhaps in April? (10)
I believe the answer is:
springtime
'april?' is the definition.
(April is part of spring)
'leap year perhaps' is the wordplay.
'leap' becomes 'spring' (leap can mean to spring or jump).
'year perhaps' becomes 'time' (year is a unit of time).
'spring'+'time'='SPRINGTIME'
'in' acts as a link.
(Other definitions for springtime that I've seen before include "Season loved by lovers" , "era of promise" , "Growing season" , "When trees are budding" .)