In sleigh before noon Frenchman crashed (7)
I believe the answer is:
slammed
'crashed' is the definition.
(I've seen this before)
'in sleigh before noon frenchman' is the wordplay.
'in' indicates putting letters inside.
'sleigh' becomes 'sled' (synonyms).
'before noon' becomes 'am' (as in AM on a clock).
'frenchman' becomes 'm' (abbreviation for Monsieur - like 'Mr').
'am'+'m'='amm'
'sled' placed around 'amm' is 'SLAMMED'.
(Other definitions for slammed that I've seen before include "Shut forcefully with loud noise" , "Criticised" , "crashed" .)