It's a fib, I never started to get up late (3,2)
I believe the answer is:
lie in
'get up late' is the definition.
(I've seen this before)
'it's a fib i never started' is the wordplay.
'it's a fib' becomes 'lie' (a fib is a lie).
'started' says to take the initial letters.
The first letter of 'never' is 'n'.
'lie'+'i'+'n'='LIE-IN'
'to' acts as a link.
(Other definitions for lie in that I've seen before include "Make a late start" , "Delay getting up" , "Long stay in bed in the morning" , "Stay in bed, be a lazybones" , "Stay late in bed" .)