Line up doctor on English ship (5)
I believe the answer is:
dress
'line up' is the definition.
(I know that line up can be written as dress)
'doctor on english ship' is the wordplay.
'doctor' becomes 'Dr' (abbreviation).
'on' is a charade indicator (letters next to each other).
'english' becomes 'e' (abbreviation).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'dr'+'e'+'ss'='DRESS'
(Other definitions for dress that I've seen before include "Clothe; decorate" , "Finish" , "This woman might slip on" , "Decorate; garment" , "what she wears?" .)