Sovereign English politician meets on ship (7)
I believe the answer is:
empress
'sovereign' is the definition.
(empress is a kind of sovereign)
'english politician meets on ship' is the wordplay.
'english' becomes 'e' (abbreviation).
'politician' becomes 'mp' (Member of Parliament).
'meets' says to put letters next to each other.
'on' becomes 're' ('on' can be mean 'with reference to').
'ship' becomes 'ss'.
'e'+'mp'+'re'+'ss'='EMPRESS'
(Other definitions for empress that I've seen before include "In Victoria, say" , "She rules over vast territories" , "Queen Victoria was one" , "leading lady" , "Female ruler" .)