Neglect to put it on order (4)
I believe the answer is:
omit
'neglect' is the definition.
(synonyms)
'it on order' is the wordplay.
'on' says to put letters next to each other.
'order' becomes 'om' (Order of Merit).
'it' after 'om' is 'OMIT'.
'to put' acts as a link.
(Other definitions for omit that I've seen before include "Exclude; forget to include" , "Leave out or forget" , "Leave out or overlook" , "Miss out" , "Leave out, perhaps in error" .)