Current fashion in leisurewear, a bit retro? (2,4)
I believe the answer is:
el nino
'current' is the definition.
(I know that El Nino is a type of current)
'fashion in leisurewear a bit retro?' is the wordplay.
'a bit' indicates a hidden word (the answer is formed by a bit of the clue).
'retro?' says the letters should be written backwards (I've seen 'retro' mean this (retro is Latin for 'backwards')).
'oninle' can be found hidden inside 'fashion in leisurewear'.
'oninle' written backwards gives 'EL NINO'.
(Other definitions for el nino that I've seen before include "Warm sea-current" , "modern opera" , "Periodic climatic phenomenon" , "Climatic event affecting world's weather" , "Pacific feature affecting climate" .)