Model admitting Mike two hours before midnight, very much in love (7)
I believe the answer is:
smitten
'very much in love' is the definition.
(as in being smitten with someone)
'model admitting mike two hours before midnight' is the wordplay.
'model' becomes 'sit' (e.g. for a painting).
'admitting' indicates putting letters inside (admit can mean to welcome in or accept).
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'two hours before midnight' becomes 'ten' (ten o'clock).
'sit' going around 'm' is 'smit'.
'smit'+'ten'='SMITTEN'
(Other definitions for smitten that I've seen before include "Much affected; struck" , "Struck (by love?)" , "Enchanted by mittens" , "Affected by something overwhelming" , "Besotted, enamoured" .)