Put off foreign one wearing old hat (7)
I believe the answer is:
daunted
'put off' is the definition.
(I've seen this before)
'foreign one wearing old hat' is the wordplay.
'foreign one' becomes 'un' (French for 'one').
'wearing' means one lot of letters goes inside another.
'old hat' becomes 'dated' (I've seen this before).
'un' inserted inside 'dated' is 'DAUNTED'.
(Other definitions for daunted that I've seen before include "Made discouraged, being undated" , "Put off" , "Disheartened, being undated" .)