Attendant's uniform in my bank (8)
I believe the answer is:
courtier
'attendant's' is the definition.
(courtier is a kind of attendant)
'uniform in my bank' is the wordplay.
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'in' is an insertion indicator.
'my' becomes 'cor' (both are expressions of surprise).
'bank' becomes 'tier' (I've seen this before).
'u' inserted within 'cor' is 'cour'.
'cour'+'tier'='COURTIER'
(Other definitions for courtier that I've seen before include "Royal attendant" , "king's follower" , "Rosenkrantz,say" , "Sovereign's attendant" , "who has Palace role?" .)