American stylist ultimately cuts facial hair for diplomat (7)
I believe the answer is:
attache
'for diplomat' is the definition.
(I've seen this before)
'american stylist ultimately cuts facial hair' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'ultimately' suggests the final letters.
'cuts' means one lot of letters goes inside another (some letters cut their way into a word).
'facial hair' becomes 'tache' (I've seen this before).
The last letter of 'stylist' is 't'.
't' going inside 'tache' is 'ttache'.
'a'+'ttache'='ATTACHE'
(Other definitions for attache that I've seen before include "Military assistant" , "Embassy employee" , "Briefcase or member of a diplomatic mission" , "Embassy official" , "Embassy member" .)