Uniform’s needed in Royal Navy career (3)
I believe the answer is:
run
'career' is the definition.
(career can mean to run or move out of control)
'uniform's needed in royal navy' is the wordplay.
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'needed in' means one lot of letters goes inside another.
'royal navy' becomes 'RN' (abbreviation for Royal Navy).
'u' inserted inside 'rn' is 'RUN'.
(Other definitions for run that I've seen before include "politician must do this to get elected" , "journey" , "Possibly an extra" , "Manage, operate" , "Unbroken series" .)