Strange French one with us initially upset man (7)
I believe the answer is:
unusual
'strange' is the definition.
(I know that strange can be written as unusual)
'french one with us initially upset man' is the wordplay.
'french one' becomes 'un' ('one' in French).
'with' says to put letters next to each other.
'initially' suggests taking the first letters.
'man' becomes 'al' (man's name).
The initial letter of 'upset' is 'u'.
'un'+'us'+'u'+'al'='UNUSUAL'
(Other definitions for unusual that I've seen before include "Not common or ordinary" , "Peculiar" , "Infrequent" , "Extraordinary!" , "Not habitually or commonly occurring" .)