Twice, Limerick University brought back Scottish singer (4)
I believe the answer is:
lulu
'scottish singer' is the definition.
'twice limerick university brought back' is the wordplay.
'twice' indicates the doubling of some letters.
'limerick university' becomes 'ul' (I am not sure about this - if you are sure you should believe this answer much more).
'brought back' says the letters should be written in reverse.
'ul' written backwards gives 'lu'.
'lu' duplicated is 'LULU'.
Can you help me to learn more?
(Other definitions for lulu that I've seen before include "Outstanding example of its kind - Alban Berg opera - Scottish pop singer, b. 1948" , "modern opera" , "Attractive girl" , "Glaswegian 60s pop singer" , "Exceptional thing (colloq.); Berg opera" .)