At the gent's, we're told, instead (2,4)
I believe the answer is:
in lieu
'instead' is the definition.
(I've seen this before)
'at the gent's we're told' is the wordplay.
'at' becomes 'in'.
'the gent's' becomes 'loo' (the gentlemen's toilet).
'we're told' indicates a 'sounds like' (homophone) clue.
'loo' is a homophone of 'lieu'.
'in'+'lieu'='IN LIEU'
(Other definitions for in lieu that I've seen before include "in place of another" , "'In place of (2,4)'" , "As a substitute" , "In place of, instead" .)