Usual man originally using the French king (7)
I believe the answer is:
regular
'usual' is the definition.
(similar in meaning)
'man originally using the french king' is the wordplay.
'man' becomes 'reg' (short for Reginald).
'originally' suggests taking the first letters.
'the french' becomes 'la' ('the' in French).
'king' becomes 'R' (abbreviation for rex, king in Latin).
The first letter of 'using' is 'u'.
'reg'+'u'+'la'+'r'='REGULAR'
(Other definitions for regular that I've seen before include "Following normal practice" , "Usual, customary" , "Habitui" , "Frequent - usual" , "Uniform, even" .)