The Frenchman at the shallow end has to start again (5)
I believe the answer is:
renew
'to start again' is the definition.
(I've seen this before)
'the frenchman at the shallow end' is the wordplay.
'the frenchman' becomes 'rene'.
'at' means one lot of letters go next to another.
'end' indicates one should take the final letters.
The final letter of 'shallow' is 'w'.
'rene'+'w'='RENEW'
'has' is the link.
(Other definitions for renew that I've seen before include "Regenerate" , "Update library book, acquaintance, etc" , "Transform born-again" , "Restore, resume" , "Revive" .)