Competent maiden making comeback as songstress (5)
I believe the answer is:
melba
'songstress' is the definition.
(Nellie Melba)
'competent maiden making comeback' is the wordplay.
'competent' becomes 'able' ('able' can be similar in meaning to 'competent').
'maiden' becomes 'm' (cricket abbreviation).
'making comeback' shows that the letters should be reversed in order.
'able'+'m'='ablem'
'ablem' reversed gives 'MELBA'.
'as' is the link.
(Other definitions for melba that I've seen before include "Dame Nellie had an ice-cream dish named after her" , "Peach --; -- toast" , "Peach -, ice cream dish" , "Australian operatic soprano, d. 1931" , "Dame Nellie --; peach --" .)