Land seen worked by girl (7)
'land' is the definition.
(Senegal is an example)
'seen worked by girl' is the wordplay.
'worked' indicates an anagram.
'by' is a charade indicator (letters next to each other).
'girl' becomes 'gal' ('gal' can be a synonym of 'girl'**).
'seen' is an anagram of 'sene'.
(Other definitions for senegal that I've seen before include "Part of Africa", "Country surrounding the Gambia", "W African republic", "Sea glen in the African state", "Dakar is its capital".)