Behaviour in Aldi somewhat lacking — the ladies won't have it (6)
I believe the answer is:
urinal
'ladies won't have it' is the definition.
(as in a ladies toilet)
'behaviour in aldi somewhat lacking' is the wordplay.
'somewhat lacking' says the answer is hidden in the clue (some letters removed to reveal the answer).
'URINAL' can be found hidden inside 'behaviour in aldi'.
'the' acts as a link.
(Other definitions for urinal that I've seen before include "public convenience" , "waste disposal unit" , "Sanitary fitting" .)