More confident female abandoning water sportsman (5)
I believe the answer is:
surer
'more confident' is the definition.
('sure' can be similar in meaning to 'confident')
'female abandoning water sportsman' is the wordplay.
'female' becomes 'f' (abbreviation).
'abandoning' indicates named letters should be taken away.
'water sportsman' becomes 'surfer' (I've seen this in another clue).
'surfer' with 'f' taken out is 'SURER'.
(Other definitions for surer that I've seen before include "faster" , "more right?" , "More certain and positive" .)