Twelve? I had nine initially in force (8)
I believe the answer is:
midnight
'twelve?' is the definition.
(twelve o'clock)
'i had nine initially in force' is the wordplay.
'i had' becomes 'I'd' (contraction).
'initially' suggests taking the first letters.
'in' indicates putting letters inside.
'force' becomes 'might' (might can mean power or force).
The first letter of 'nine' is 'n'.
'id'+'n'='idn'
'idn' going inside 'might' is 'MIDNIGHT'.
(Other definitions for midnight that I've seen before include "Pitch darkness" , "12 hours from noon" , "12 in the evening" , "When the day changes" , "Twelve o'clock" .)