Makes waves, seeing mostly improper evening shifts (9)
I believe the answer is:
undulates
'makes waves' is the definition.
'mostly improper evening shifts' is the wordplay.
'mostly' means to remove the last letter.
'improper' becomes 'undue' (I've seen this before).
'evening shifts' becomes 'lates'.
'undue' with its final letter removed is 'undu'.
'undu'+'lates'='UNDULATES'
'seeing' is the link.
(Other definitions for undulates that I've seen before include "Moves in a wavy pattern" , "Moves like waves" .)