Specialist on staff cheers up, given facial adornment (7)
I believe the answer is:
attache
'specialist on staff' is the definition.
'cheers up given facial adornment' is the wordplay.
'cheers' becomes 'ta' (both can informally mean thank you).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'given' says to put letters next to each other.
'facial adornment' becomes 'tache' (short for moustache).
'ta' reversed gives 'at'.
'at'+'tache'='ATTACHE'
(Other definitions for attache that I've seen before include "One on embassy staff" , "This small rectangular case carries documents" , "Diplomatic official" , "Member of ambassador's staff" , "That ace (anag.)" .)