Frenchman, perhaps, with British army corps (5)
I believe the answer is:
andre
'frenchman perhaps' is the definition.
'with british army corps' is the wordplay.
'with' becomes 'and' (I've seen this before).
'british army corps' becomes 're' (Royal Engineers).
'and'+'re'='ANDRE'
(Other definitions for andre that I've seen before include "Name of pianist" , "- Previn; - Gide" , "Gide, perhaps" , "Pop singer and reality TV star" , "Australian who sings" .)