Surprising success surrounding sailor's customary dress (5)
I believe the answer is:
habit
'customary dress' is the definition.
'habit' can be an answer for 'dress' (habit is a kind of dress). I'm not sure about the 'customary' bit.
'surprising success surrounding sailor's' is the wordplay.
'surprising success' becomes 'hit' (hit is a kind of success. I am not sure about the 'surprising' bit.**).
'surrounding' means one lot of letters goes inside another.
'sailor' becomes 'ab' (abbreviation for able seaman).
'hit' enclosing 'ab' is 'HABIT'.
Can you help me to learn more?
(Other definitions for habit that I've seen before include "Ingrained behaviour" , "can cause addiction" , "Breaking this is hard" , "It's worn in order" , "Dress - custom - practice" .)