Think I'm home in time (7)
I believe the answer is:
imagine
'think' is the definition.
('imagine' can be a synonym of 'think')
'i'm home in time' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'in' means one lot of letters goes inside another.
'time' becomes 'age' (age is a kind of time).
'in' inserted within 'age' is 'agine'.
'im'+'agine'='IMAGINE'
(Other definitions for imagine that I've seen before include "Conjure up in mind,fancy" , "Picture mentally" , "Reckon" , "Believe to be so, suppose" , "John Lennon hit" .)