Ladies for example in Cromwell Avenue (3)
I believe the answer is:
lav
'ladies' is the definition.
(the ladies' lavatory)
'in cromwell avenue' is the wordplay.
'in' indicates the answer is hidden within the clue.
'LAV' is hidden in the letters of 'cromwell avenue'.
'for example' acts as a link.
(Other definitions for lav that I've seen before include "toilet" , "Private place in short" , "Loo" .)