Staff given a hint: uniform is missing cuff (7)
I believe the answer is:
manacle
'cuff' is the definition.
(synonyms)
'staff given a hint uniform is missing' is the wordplay.
'staff given' becomes 'mana' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a hint' becomes 'clue' (synonyms).
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'is missing' is a deletion indicator.
'clue' with 'u' removed is 'cle'.
'mana'+'cle'='MANACLE'
(Other definitions for manacle that I've seen before include "Fetter" , "item restricting movement" , "Shackle on the wrist" , "Handcuff" , "restricting at the cuff?" .)